ISTANBUL - An explosion occurred in Istanbul's international Sabiha Gokcen airport on Wednesday, wounding two cleaning staff, a local official said.

"An unknown explosion happened at around 2 am local time (0000 GMT) in the area, where the plane parked," Istanbul Governor Vasip Sahin announced.

Two women cleaning staff were wounded on a nearby plane belonging to Turkish Pegasus Airlines and were taken to the hospital, Pegasus Airlines said in a written statement.

The cause of the explosion is still not clear.

Heavy security measures were taken in the area while police forces and fire engines were dispatched to the airport.

Police started an extensive investigation at the airport, which is located on the Asian side of the city.

Special teams with long barreled weapons backed up with helicopters have been searching the cars in the area.