Kabul, AfghanistanCNN — 

At least 19 people have been killed and 27 others injured in Afghanistan’s capital Kabul following a suicide bomb blast at an education center, the city’s police said.

The explosion took place at the Kaaj education center, where students were taking a practice university entrance exam Friday morning at 7:30 a.m., local time (11 p.m. ET), Kabul Police Spokesman Khalid Zadran told CNN.

“Unfortunately, the explosion has caused human casualties. Security forces have reached the area and we will share the type of the explosion and casualty figures later,” Zadran added.

There has been no claim of responsibility for the attack.

A string of attacks in Kabul have claimed dozens of lives in recent weeks.

Earlier this month, two Russian embassy employees were among six people killed in a suicide blast near the Russian embassy, and in August, an explosion at a mosque during evening prayers killed 21 people and injured 33 more.