A freight train carrying ammonia derailed in eastern Serbia on Sunday, injuring dozens and blocking a major international highway.

 The Associated Press writes about it.

 A state of emergency was declared in the city of Pirot, and the authorities asked residents not to leave their homes. Dozens of people were hospitalized.

 According to the Serbian portal RTS, more than 50 people were hospitalized with symptoms of ammonia poisoning. One person is also reported to have died, but it is not known if it is related to poisoning.

 The accident reportedly caused a group of 20 tankers to derail, at least one of which fell into the Nishava River bed, causing a violent reaction of ammonia upon contact with water.

 Due to limited visibility caused by the leak, several cars crashed on the main highway leading to Bulgaria during the busy Christmas holiday rush.

 Police closed the highway and diverted traffic to local roads. The cause of the train derailment is currently unknown.

 Leaking ammonia gas can be flammable and cause serious injury or even death.