TIRANA (Reuters) - At least 11 Albanian university students were killed and 22 others injured when their bus plunged hundreds of feet into a ravine on Monday, police said.

The injured, some in critical condition, were rushed to hospital in the capital Tirana by helicopter.

"Preliminary information says 11 are dead and 22 are injured," state police said.

Some media reports said two buses had left the central Albanian town of Elbasan with 40 and 35 students on board for a two-day study tour. Others said the university students were returning from a holiday in Albania's southernmost corner, off Greece's Corfu island.

The government declared Tuesday a day of national mourning.

(Reporting By Benet Koleka)