A group of students was studying outside an Afghan school Tuesday when a rocket slammed into the school yard, killing at least seven children and wounding dozens more.

Police blamed Taliban militants for the rocket attacks -- two in total. The second one exploded in an open field and no one was injured.

However, it's not clear if the target of the first rocket was the Salabagh School in Asadabad, capital of the eastern province of Kunar, near the Pakistani border.

Police blame Taliban militants, alleging it was part of their campaign against government-sponsored education. However, the school is close to a U.S. base that frequently comes under attack.

Hundreds of boys aged 6 to 16 were in the school yard at the time of the attack, because there wasn't enough room in the school buildings, said Mohammed Hasan, a police commander in the city in volatile eastern Kunar province.

Six children were killed by the shrapnel and dozens more were injured, including a teacher and a janitor. The wounded were taken to hospital at the U.S. base.

A reporter told the Reuters news agency that about 30 people were taken to hospital to be treated for their injuries, and 10 were discharged after treatment.

Omar Sahib, 12, described a scene of horror after the rocket hit.

"I saw so many children on the ground. Many were not moving. Screams were coming from everywhere. I was crying," he told The Associated Press. "One teacher was lying there without a leg."

Dozens of schools have been attacked since U.S.-led forces ousted the Taliban in 2001. Most of the attacks have come at night, and have not caused any casualties.

The Taliban believe educating girls is against Islam, and only want boys to learn religion.

More than 2,000 Canadian troops are in Afghanistan as part of a coalition force that have faced increasing attacks from the Taliban, al Qaeda and other groups.

With files from The Associated Press