Law enforcement personnel managed to quickly repulse the attack by as many as three gunmen, an assault claimed by a resurgent Taliban who warned its violence "wasn't over yet."
And as Pakistan launched new airstrikes on militants in its northwestern tribal region, questions arose whether Prime Minister Nawaz Sharif would abandon government-sponsored peace talks with them for an aggressive military offensive.
Television stations aired footage of security guards frantically taking up positions behind buildings or earthen berms at the training facility, roughly 1 kilometer (a half mile) from Karachi's Jinnah International Airport, where the Taliban attacked Sunday night. The Pakistani military also sent soldiers to assist.
Airport Security Force spokesman Ghulam Abbas Memon said two to three gunmen tried to enter the training academy from two different entrances.
"Our men retaliated and repulsed" the gunmen, Memon said.
Col. Tahir Ali, a senior official with the Airport Security Force, said two militants fired toward a hostel for female employees on the academy grounds. He said no one was hurt.
The Civil Aviation Authority, which is responsible for running the country's airports, initially said on Twitter that all flights at the airport were suspended but later reported that operations had resumed.
"The aim of the attackers was to create a panic, and we shouldn't be playing into their hands," the head of the airport security force, Azam Khan, told Pakistani television.
The attackers escaped into the vast slum that borders the airport. Karachi is a sprawling city of at least 18 million people, and members of the Pakistani Taliban in recent years have migrated to the city from the northwest to escape military operations and drone strikes there. The result has been a steep deterioration in Karachi's security.
Tuesday's firefight came on the heels of a ferocious siege Sunday night by 10 Taliban fighters who stormed a VIP and cargo terminal at the Karachi airport in an attack that killed 26 people and the Taliban gunmen. At least 11 members of the Airport Security Force were killed during that attack.
Pakistani authorities discovered more bodies from that siege Tuesday morning. Airport authorities found seven bodies in a burned building at the airport, charred beyond recognition, said the head of the Karachi Municipal Corporation, Rauf Akhtar Farooqi.
The discovery of the bodies, roughly a day after Pakistani officials said the airport had been secured, will raise more questions about security at the country's busiest airport.
Relatives of the dead reported receiving telephone calls from their loved ones trapped inside the burning building.
"The last I spoke to him, he said there was intense firing going on and that a building was also on fire," said Junaidul Haq, whose brother died. Pakistani media reported that the seven were airport workers who hid from the fighting but got trapped and burned to death.
The head of the Civil Aviation Authority, Mohammad Yusuf, said authorities tried twice to reach the burning building during the siege but came under fire. After security officials cleared the airport, they went back to search the building because there were reports of people trapped inside.
The Pakistani Taliban has been trying to overthrow the government and establish its hard-line rule across the country. Prime Minister Nawaz Sharif's government repeatedly has tried to negotiate with the militants to end the fighting but those efforts have collapsed.
The airport attack has raised questions about whether Sharif, who campaigned on peace talks with the Taliban, will continue to pursue the negotiations policy or choose a more aggressive, military response. Supporters of peace talks argue that negotiations are the only way to end the cycle of violence, while critics say a deal will allow militants to regroup and strike back with more force.
Early Tuesday, Pakistani military airstrikes targeted the Tirah Valley in the country's northwest. The military said it killed 25 suspected militants in strikes on nine hideouts, but the information could not be independently verified. The area is part of a lawless terrain along the Afghan border that is home to a mix of local militants and al-Qaida-linked foreign fighters.
Santana reported from Islamabad. Associated Press writers Asif Shahzad and Zarar Khan in Islamabad contributed to this report.
Follow Rebecca Santana on Twitter at www.twitter.com/ruskygal .
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