An explosion on the tarmac at Turkey’s Sabiha Gökçen International Airport in Istanbul killed one person and wounded another.

Cleaner Zehra Yamac, 30, was working on a nearby Pegasus airplane when the explosion occurred at 2 a.m. local time. The plane was parked off to the side, away from passenger areas.

She later died of head injuries.

“There were no passengers either on the plane or on the stairway. Sabiha Gokcen airport is continuing its normal operations,” stated Pegasus.

The airport told the media they are investigating the explosion, but aviation experts told The Telegraph it has all the makings of a bomb.

“It is too early at this stage to have any definitive thoughts, but what stands out most is what appears to be shrapnel damage on the airport windows, plus the damage done to planes some distance away,” explained Matthew Finn, managing director of aviation security firm Augmentiq. “All of these point to it being some kind of bomb.”

He added, “Other scenarios don’t really stand up. There are things like the cooker in the galley of a plane that could malfunction and hurt someone, but the blast radius is so wide that it looks like it was some kind of device. The question then is how did it get into the airport, and what is security like there?”

Turkey heightened its security awareness after suicide bombers killed 103 people in Ankara on October 10. The government blamed the Islamic State (ISIS/ISIL) for the attack. Turkey is also in a three-decade war with the Kurdistan Workers’ Party (PKK), a far left organization. The war regained steam over the summer due to deadly attacks on both sides. The Revolutionary People’s Liberation Party-Front (DHKP-C) has also attacked Istanbul in the past few months.

Police added more security at the airport’s entrances.

Transport Minister Binali Yildirim said that five planes were damaged, but airport workers are repairing them in the hangars. He insisted no one knows the cause and the airport is not weak in security.

“At this moment it’s too early to give a verdict but I want to emphasise there is no weakness concerning security,” he said.

Malaysia Airports Holding purchased the airport this year.

“We are working very closely with the Turkish government and our counterparts to facilitate the investigation, and we await their official report on it,” declared Dato’ Azmi Murad, the executive director of Sabiha Gökçen. “The Turkish government has heightened security within the vicinity of the airport, which includes helicopter surveillance.”