At least 15 people were killed and dozens injured on Monday when an elevated metro line collapsed in Mexico City.

Here are some of the worst accidents on metros over the past four decades:

- July 15, 2014 - RUSSIA: At least 22 people die and more than 200 are injured after a train derails on Moscow's packed metro during the rush hour.

- June 22, 2009 - UNITED STATES: A head-on collision between two subway trains in Washington leaves nine people dead and more than 70 injured.

- July 3, 2006 - SPAIN: In the eastern city of Valencia, a metro train traveling at twice the speed limit of 40 kilometers (25 miles) an hour derails, leaving 43 dead and 39 injured.

- February 18, 2003 - SOUTH KOREA: A fire started by a man trying to commit suicide destroys two metro trains, killing 198 and injuring 147 in Daegu, in the southeast.

- October 28, 1995 - AZERBAIJAN: 292 people die and 168 are injured when a fire breaks out on the Baku metro when a train is between two stations.

- November 18, 1987 - BRITAIN: A fire on a wooden escalator in London's King's Cross underground station kills 31 and injures 150.

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- February 4, 1977 - UNITED STATES: In Chicago, an elevated railway train topples on to the street below after being hit by another train. Eleven are killed and more than 200 injured.

- October 20, 1975 - MEXICO: In Mexico City, two metro trains ram into each other leaving 23 dead and 55 injured.