NEW DELHI — At least 36 passengers were killed in a train derailment in southern India Saturday night, the latest disaster on India’s old and overburdened railway system.

Government and medical authorities said at least 40 additional passengers were injured, several critically, and admitted to nearby hospitals.

Rescue workers struggled into the early morning to pull injured passengers and dead bodies from the engine and nine coaches, authorities said.

The crash took place in the Vizianagaram district of Andhra Pradesh state in southern India, when the engine and coaches of the Hirakhand Express from Jagdalpur to Bhubaneshwar derailed at 11:15 p.m., according to a statement issued by Indian Railways, the state-owned firm that runs India’s trains.

Authorities said the cause was not clear, and Indian Railways announced an investigation.

India’s railways, which transport 23 million people per day over more than 70,000 miles of track, have been neglected for years. In 2014, there were more than 27,000 train-related deaths in India.

In November, more than 140 passengers died in the derailment of passenger coaches near the city of Kanpur. In the weeks after that accident, two more people died in another derailment of passenger coaches in the same stretch of track.

In 2012, a committee appointed to review the safety of the rail network cited “a grim picture of inadequate performance largely due to poor infrastructure and resources.’’

It recommended a slew of urgent measures, including upgrading tracks, repairing bridges, eliminating level crossings, and replacing old coaches with safer ones that would better protect passengers in case of an accident.

These remedies came with a hefty price tag: The committee said it would cost some $14 billion over five years to put the railways on safer footing. Still, it advised that the work should proceed “in a time-bound manner with required resources mobilized.’’ This was never done.

Enku Swamy, the district fire officer for Vizianagaram, said in a telephone interview that rescue agencies took about 40 minutes to reach the accident site, in a remote area close to the border of Odisha state.

“Some people died because of a stampede inside the derailed coaches,’’ Swamy said.

Madan Mohal Nial, 21, a passenger, said in an interview from his hospital bed that he was making the journey to take an exam for a government job when the derailment happened.