ISTANBUL - At least six people were injured on Wednesday when a shuttle bus in Istanbul was hit by an explosion, local media reported.

The blast happened in the district of Pendik on the Asian side of Istanbul, as the shuttle bus was heading to Sabiha Gokcen Airport, the IHA news agency said.

The agency said university students are among the injured, as the shuttle bus belongs to a private university.

Police have launched an investigation and believe the large-scale damage to the bus was caused by handmade explosives, press reports said.

Istanbul is a frequent target of terror attacks over the past year.