At least 21 people were killed on Sunday after terrorists attacked the international airport in Karachi in Pakistan, CNN reports.

Officials at Jinnah Hospital in Karachi said the dead included eight members of airport security forces, two Pakistan International Airlines employees and one ranger. Ten terrorists were also killed in the clashes.

The clashes broke out after attackers armed with grenades stormed the airport through three entrances, said Ahmad Chinoy, director-general of the citizen’s police liaison committee.

One terrorist blew himself up in front of an armored car, leaving some people inside the vehicle critically injured, Chinoy said.

All flights at the airport have been canceled, and some passengers are trapped in a lounge area, he added, according to CNN.

The violence started in a cargo and VIP area of the airport late Sunday night and continued for more than five hours into Monday morning, sending a plume of smoke over the airport.

A cargo plane was damaged and set ablaze in the fighting, Chinoy said. The airport’s cargo area is about a kilometer (0.62 miles) away from the area where commercial planes take off.

Terror attacks have become more and more common with the rise of the Taliban in Pakistan.

In January, a Pakistani high school student tackled a suicide bomber attempting to blow up his school in the Hangu region of the country. 15-year-old Aitzaz Hasan was killed, but he saved the lives of his schoolmates in the heroic act.