At least 11 people were killed when men dressed in security uniforms opened fire with automatic weapons and grenades, CNN reported. The ten gunmen were dead, while no passengers were injured or aircraft hijacked, the Pakistani army said in a post on Twitter.

There was no immediate claim of responsibility for the attack, though Taliban militants have engaged in an insurgency that seeks to impose Islamic law on the country. Peace talks that began in March with Tehrik-e-Taliban, a loose alliance of Taliban fighters, have stalled, raising the prospect of stepped up attacks in a campaign that has killed 50,000 people since 2001.

The attack took place at a terminal used for cargo and other flights separate from the main passenger terminals of Jinnah International Airport. Television images showed some of the gunmen arriving at a security checkpoint late last night in a white van and opening fire on guards before driving into the compound. Gunmen entered the site at three different points, CNN reported.

The attackers then set off a series of explosives, and fires could be seen raging at the airport, sending plumes of black smoke into the sky over Karachi. The army moved in and the ensuing siege lasted at least five hours.

Flights into and out of Pakistan’s largest city were suspended, said Civil Aviation Authority spokesman Abid Qaimkhani.

Bilwal Bhutto Zardari, son of the murdered Prime Minister Benazir Bhutto and chairman of the Pakistan Peoples Party that runs the government in the Karachi area, condemned the attack, according to Asif Waheed, a spokesman for Zardari.