Fifteen policemen were killed on Tuesday when a helicopter fell to the ground and burst into flames in a wooded region of northwestern Colombia, the National Police said. Police said the US-made UH-60 Black Hawk apparently suffered a mechanical failure while taking part in a counter-narcotics operation in the department of Antioquia some 450 km northeast (280 miles) of the capital of Bogota. 'As a result of this incident, 15 policemen were killed and two others wounded,' the police said in a statement. The crash comes four days after 11 soldiers were killed when a Spanish-made CASA C-235 suffered motor failure and crashed in the northeast of the country. The policemen killed on Tuesday were taking part in a crackdown on a criminal gang known as 'Clan Usuga,' made up of former right-wing paramilitaries.