A pair of suicide bombers killed at least 29 people Tuesday night at a Shiite mosque in Herat, Afghanistan, a provincial spokesman said.

Another 64 people were wounded, said Jelani Farhad, the Herat provincial spokesman.

The blasts took place during evening prayers.

The attack started when one suicide bomber began firing on worshippers inside the mosque before blowing himself up, said Abdul Ahad Walizada, spokesman for the police chief.

Suicide bombers killed and injured dozens Tuesday night at a Shiite mosque in Herat, Afghanistan.

"Two attackers entered the mosque and started shooting and throwing grenades at people," Mohammad Adi, a survivor, told Reuters.

The second bomber was among the crowd of worshippers when he blew himself up, Walizada said.

Video from Reuters showed police inspecting bodies inside the mosque. Some people carried bodies in blankets, the video showed.

Officials fear the death toll could rise, because 10 of the wounded are in critical condition, said Dr. Arif Shahram, the director of Herat Regional Hospital.

It was not immediately clear who was responsible for the attack.

-cnn