A suicide bomber struck outside the Afghan Supreme Court in Kabul Tuesday, close to the US embassy and International Security Assistance Force's (ISAF) headquarters.
A police source said the explosion was heard around 4:20 p.m. local time and was near the Supreme Court compound, just 200 meters from the US embassy, according to Reuters.
The Associated Press cited deputy police chief Dawood Amin saying the explosion was a few hundred yards from the embassy's gates, but noted that the actual embassy building is farther away.
Police spokesman Hashmat Stanikzai said the attack was the work of a suicide bomber in an SUV.
The Taliban claimed responsibility for the attack, and reportedly threatened more attacks on Afghanistan's judiciary if it sentenced members of the Taliban's militia to death.
"The bomber in a car struck and killed up to 50 ruthless prosecutors and other workers," Taliban spokesman Zabihullah Mujahid said, exaggerating the attack's death toll.
General Mohammad Zahir, the head of Kabul criminal investigations, told AFP, "Most of the casualties are Supreme Court employees."
ISAF's twitter account posted the following updates:
UPDATE:Reports say several killed and wounded in the blast near Supreme Court in Kabul.
— ISAF (@ISAFmedia) June 11, 2013
The US embassy in Kabul put out a travel warning, restricting embassy movements and advising US citizens to be cautious.
It said, "US citizens traveling to Afghanistan despite this warning should avoid being predictable in their movements, including varying routes and times in commutes or other routine travel. The US Embassy urges US citizens to remain vigilant and avoid areas where westerners congregate, such as hotels and guest houses."
Tuesday's attack coincided with the UN's Afghanistan representative, Jan Kubis, saying the Taliban and similar insurgent groups were responsible for the surge in civilian deaths in the last six months. According to Reuters, 3,092 civilians were killed or wounded between January and June 6, a 24 percent increase compared to last year.
Kubis had announced the Taliban were prepared to talk with the UN about ways to reduce civilian deaths. "I can confirm that we received signals about their willingness and readiness to discuss these issues with us. I welcome this," he said.
Afghanistan President Hamid Karzai condemned the bombing - the most deadly since an attack in Kabul on Dec. 6, 2011, killed at least 80 people - and called it a "terrorist act that once again shows the Taliban are serving the enemies of Islam."