At least 11 people, including a judge, have been killed in a suicide attack on a court in the centre of the Pakistani capital Islamabad, police said.
At least 30 people were also injured, and two lawyers and a police officer were among the dead following the attack on Monday, police told Al Jazeera.
Police said two suicide bombers wearing explosive vests rushed into the court complex, threw hand grenades, started shooting, and then blew themselves up, Islamabad Police Chief Sikander Hayat told the Associated Press news agency.
"It was certainly an act of terrorism,'' Hayat said in televised comments to reporters.
Police told Al Jazeera it did not appear to be a targeted attack, as the judge was not involved in any anti-terrorism court cases, and the attackers had been firing indiscriminately.
Ahmed Khan Awan, a district court judge, was identified as one of the fatalities, our correspondent said.
The explosions sent lawyers and judges running for their lives as police stormed in. Hayat said police subsequently searched the entire complex and found no additional attackers.
"The attackers were armed with Kalashnikovs and hand grenades," said lawyer Murad Ali Shah, who was in the complex.
"They were wearing shalwar kameez and had long beards and long hair."
Officers at the scene in the city's F-8 sector told the AFP news agency that the incident began when a defendant was brought before the court and his friends tried to rescue him.
"I heard firing in the other court, so I ran to save myself," Raja Adnan, a lawyer, told Al Jazeera. "I heard screams from people for a while, and stayed inside under cover to save my own life."
Pakistan has been in the grip of a bloody homegrown Taliban insurgency since 2007 but attacks within the capital have been very rare in recent years.
The Taliban, which declared a month-long ceasefire over the weekend, has denied involvement in the attack and no one immediately claimed responsibility.
Pakistani television showed images of the area with windows blown out, walls torn and lawyers wearing the traditional black suit worn by all Pakistani lawyers carrying what appeared to be dead and wounded from the buildings.
Policemen with weapons raised ran through the area and searched offices fearing that there might be more attackers, according to our correspondent, who was reporting from Islamabad.