Pakistan security officials are interrogating at least four people captured after an attack by militants on a police academy in Lahore.
Eighteen people, including two civilians, eight policemen and eight gunman were killed and 95 people were injured during the eight-hour battle to wrest back control of the academy, the interior ministry says.
The chief of the Pakistani Taliban, Baitullah Mehsud, told the BBC his group was behind Monday's deadly attack.
He said the attack was "in retaliation for the continued drone strikes on by the US in collaboration with Pakistan on our people", Mr Mehsud said.
He also claimed responsibility for two other recent deadly attacks.
Mr Mehsud said such attacks would continue "until the Pakistan government stops supporting the Americans".
The attack came less than a month after gunmen attacked the Sri Lankan cricket team in Lahore. In that attack, six policemen were killed, while up to 14 gunmen escaped.
In the past year, Pakistan has seen a dramatic increase in bomb and suicide attacks carried out by insurgents.