Vehicles burn after the blasts in Lahore on Tuesday. (Reuters)

Lahore, Feb. 4: A suicide attack at a naval college killed seven persons and injured another 21 today, officials said, underlining the security challenge facing the winners of Pakistan’s landmark elections.

The attack occurred when two bombers rode up to the gate of the parking lot at the Pakistan Navy War College on a motorcycle, Lahore police chief Malik Iqbal said.

The passenger dismounted and destroyed the gate, allowing his accomplice to ride inside and unleash a much more powerful blast, Iqbal said.

“The first blast was low intensity and was meant to crash the gate. The other blast was high-intensity and was aimed at causing big losses,” Iqbal told reporters at the scene.

He said the seven dead and 21 wounded were all employees of the college. None were senior military officials, he said. However, interior ministry spokesman Javed Iqbal Cheema said a car bomber had rammed a navy bus on its way into the compound and other explosions were caused by the fuel tanks of parked vehicles.

It was not immediately possible to reconcile the differing accounts. The police chief said investigators were still gathering body parts and debris from the scene and that it was too early to speculate about who was responsible.

Earlier, television footage showed black smoke billowing from inside the college compound and several injured people with bloodstained clothes walking out. Two wrecked cars and a half-dozen damaged buses were visible behind the mangled metal gates.

Muhammad Safdar, a 23-year-old chauffeur, said he had dropped off an officer at the college and was sitting in the canteen when he heard the first blast and rushed outside.

“There was smoke and vehicles on fire... several people were lying on the ground injured and crying for help, but I too was injured as something hit me in the neck,” Safdar told reporters.

Security personnel quickly sealed off the area, a high-security neighbourhood that includes the state governor’s residence, a luxury hotel and several government offices.

Asif Ali Zardari, Pakistan People’s Party co-chairman, condemned the bombing as “inhuman, barbaric and most despicable”.

President Pervez Musharraf said the government “would not be cowed down by such acts and expressed resolve of the country to continue the fight against extremism and terrorism”, the Associated Press of Pakistan reported.