A suicide bomber targeted a Shiite Muslim mosque in northwest Pakistan on Friday, killing 19 people and wounding dozens as worshippers poured out of weekly prayers, officials said.

The bomber detonated explosives packed into a motorcycle in a narrow lane containing both the Shiite and a Sunni Muslim mosque in the town of Hangu, long a flashpoint for sectarian violence against minority Shiites.

“It was a suicide attack which targeted Shiites but Sunni Muslims also fell victim since their mosque and some shops were also very close to the site,” district police chief Mian Muhammad Saeed told reporters.

“We have found the head of the bomber, who came there on a motorbike,” he said, putting the death toll at 19 with 33 others wounded.

Police said the bomb exploded as Shiites were leaving Friday prayers and Sunnis were going into their mosque for the main weekly sermon.

“Both the Shiite and Sunni mosques are very close to each other, and the explosion took place just as Shiites were coming out of the mosque and Sunnis were going into their mosque to say Friday prayers,” said police official Imtiaz Shah.

Hangu is close to Pakistan’s semi-autonomous tribal belt on the Afghan border where Taliban and al-Qaeda-linked militants have carved out strongholds.

There was no immediate claim of responsibility for the attack.

On January 9, a devastating twin suicide attack killed 92 Shiite Hazaras in the southwestern city of Quetta – the worst single attack on Shiites in Pakistan.

According to Human Rights Watch, last year was the deadliest year on record for the country’s Shiites, with more than 400 killed, mostly in drive-by shootings.