A police officer of the Indian Railway Protection Force (RDF) was arrested after killing a senior official and 3 passengers on a train near Mumbai city.
Police said they are trying to establish the motive and identify the dead passengers.
The incident took place around 5:30 am local time on a train heading to Mumbai city.
According to a statement from the RDF, the accused first opened fire at the assistant sub-inspector, then shot 3 passengers.
The accused then activated the alarm used to stop trains in emergencies and fled. Police caught the accused in Mumbai.