Sri Lanka's military shot down two Tamil Tiger aircraft that were flying an air raid on the capital Colombo.
The military said two people were killed when one plane plunged into a government building and hospitals report at least 40 were injured.
The military said one plane was gunned down by anti-aircraft fire over the international airport, while the other was shot and crashed into the Inland Revenue building in Colombo's Fort area.
Separatist Tamil Tiger rebels, cornered in a rapidly shrinking war zone, have a fleet of small planes that they have used to carry out attacks in the past.
Although most of their territory has been taken by the rapid military advance, none of their small single-engined planes have been found by troops.
The Sri Lankan civil war, the longest-running conflict in Asia, has killed 70,000 people since it began in 1983.
