The death toll could rise further as rescuers continue work, and with many of the injured in critical conditions.
The cause of the crash is not known, although reports said a fractured rail could be to blame.
Train accidents are fairly common in India, where much of the rail infrastructure and rolling stock is out of date.
Early on Monday the railway ministry published a list of names of injured passengers. Out of the 180 listed, 56 were said to be "grievously injured".
The derailment had the strongest impact on the first two carriages of the train, which crashed into each other and overturned. Most of the victims were located in these carriages.
According to the Indian Express the carriages were outdated. The report said the government had promised earlier this year to upgrade all trains.
The train may have also been carrying far more passengers that it was supposed to, reports said.
Although the official number of passengers was about 1,200, the Times of India said as many as another 500 could have been on the train without tickets, citing unnamed railway officials as sources.
Survivors, most of whom were sleeping at the time of the crash, described horrific scenes.
"I woke up suddenly around 3.10am and felt a tremor. The train came to a screeching halt. All of a sudden, I was crushed under a crowd of people… everyone was screaming for help," survivor Yaqoob Ahmed told the Hindustan Times.
"There was a loud sound like an earthquake. I fell from my berth and a lot of luggage fell over me,'' another passenger named Ramchandra Tewari was quoted by AP as saying. "I thought I was dead, and then I passed out.''
Anxious relatives of missing passengers have reached the scene. One man from Patna said he spotted a hand sticking out in the debris wearing a ring which he recognised as his brother's.
"I'm certain that it's my brother's body but it's not been removed yet," he told the BBC.
Indian Prime Minister Narendra Modi tweeted: "Anguished beyond words on the loss of lives due to the derailing of the Patna-Indore express. My thoughts are with the bereaved families.
"Prayers with those injured in the tragic train accident."
Mr Modi also promised compensation to the victims' relatives and injured passengers, and said he had spoken to Railways Minister Suresh Prabhu.
On his own Twitter account, Mr Prabhu warned that "strictest possible action will be taken against those who could be responsible for accident".
India's worst rail disasters
- Bihar, 6 Jun 1981: 250 deaths confirmed as passenger train derails on a bridge and plunges into the Baghmati river. Hundreds more are never found, with an estimated death toll ranging from 500 to 800
- Firozabad, 20 Aug 1995: 358 people are killed as an express train hits a stationary express train
- Khanna, 26 Nov 1998: At least 212 killed as a train collides with a derailed train
- Gaisal, Assam, 2 Aug 1999: At least 290 killed as two trains carrying a total of 2,500 people collide
- Rafiganj, 10 Sept 2002: Rajdhani Express derails on bridge, killing at least 130
- West Midnapore, West Bengal, 28 May 2010: The Calcutta-Mumbai passenger train derails, killing at least 100. Police blame Maoist sabotage of the track
Bihar, 6 Jun 1981: 250 deaths confirmed as passenger train derails on a bridge and plunges into the Baghmati river. Hundreds more are never found, with an estimated death toll ranging from 500 to 800
Firozabad, 20 Aug 1995: 358 people are killed as an express train hits a stationary express train
Khanna, 26 Nov 1998: At least 212 killed as a train collides with a derailed train
Gaisal, Assam, 2 Aug 1999: At least 290 killed as two trains carrying a total of 2,500 people collide
Rafiganj, 10 Sept 2002: Rajdhani Express derails on bridge, killing at least 130
West Midnapore, West Bengal, 28 May 2010: The Calcutta-Mumbai passenger train derails, killing at least 100. Police blame Maoist sabotage of the track
Why do India's trains keep going off the rails?
What could have led to India's worst train crash in six years, according to junior railways minister Manoj Sinha, was a "fracture in the railway track leading to the jamming of wheels". This isn't the first time that India's railway tracks have come under scrutiny.
So why are trains in India going off the rails? Let's look at some facts:
- A total of 168 people died in 131 railway accidents in India in 2014-2015, up from 103 fatalities in 117 accidents in 2013-2014. (India's accident rate per million train kilometres - 0.20 - in 2012-13 compares favourably with that of advanced railways in Europe - Germany and France, for example, both recorded 0.17 accidents per million train kilometres in 2012 - but India's figures mask major deficiencies.)
- Derailment was the reason for 60 of the 131 accidents in 2014-2015. (Derailment was responsible for 962 of the 1,201 rail accidents in 1965-66, so the numbers have also gone down.)
- The majority of these accidents - 115 - were attributed to human failures - "failure of railway staff and failure of persons other than railways staff". Curiously, track failures, according to official data, did not contribute to a single accident.
But some experts believe that this doesn't quite square up with the state of India's railway tracks. Now, consider this:
- India has nearly 115,000km (71,457 miles) of railway tracks.
- A 2015 assessment by the railways ministry says some 4,500km of track should be "renewed" every year.
- But a lack of funds has meant that construction of new tracks and replacement of the old are not happening at the desired pace. Only 2,100km of tracks were targeted for "renewal" in 2015.
The fracturing of tracks - often caused by expansion of tracks in summer, and contraction in winter - is "the nightmare of the [railways] engineering department", an internal railways memo in 2014 said. "Winter is approaching very fast. All preventive steps like winter patrolling, testing etc should be ensured to detect rail and weld fractures well in time." One report said 136 cases of fractured tracks had been detected and repaired between January and May this year.
That's not all.
Funds are needed to replace outdated carriages, which comprise the bulk of the 53,000-strong fleet. Crashes between trains and vehicles account for a large number of accidents - there are still more than 10,000 unmanned crossings in India.
At the root of India's scrappy railway safety standards is lack of funds and chronic under-investment. Last year's assessment admitted that "investments in safety have been insufficient".
Former railway minister Dinesh Trivedi told me that India's railways were "bankrupt". "The focus has shifted from operations to cosmetic changes," he said.
Revenues have indeed plummeted - they grew by only 4.6% in 2015-16, lower than the 10-19% growth in the previous four fiscal years. Reason: declining freight because of an economic slowdown and a slight fall in passenger bookings.
Prime Minister's Narendra Modi's government has announced a showpiece bullet train project and more high speed trains, improved passenger amenities and free wi-fi at stations. But many say it first needs to ensure that passengers complete their journeys alive.