At least 16 people were injured Sunday morning in a hand grenade attack in Khost city, the provincial capital of Afghanistan's eastern Khost province, a provincial health official said.

"A total of 15 civilians and a policeman, who were injured in a blast, have been admitted to a provincial capital hospital Sunday morning," head of the hospital in Khost city, Majid Mangal told Xinhua.

According to locals, who witnessed the incident, the attack occurred at around 08:45 a.m. local time in Markazi Chaok, a big traffic circle in the center of Khost city, some 150 km southeast of Kabul.

"The target was a police unit which was on routine patrol in Markazi Chaok and was searching vehicle in a traffic stop but a unknown man hurled a hand grenade in the area that injured some 17 people," a witness named Pacha Gul told Xinhua near the scene.

However, Mangal said many of the injured were civilians who sustained minor injuries but three injured were in critical conditions.

No group has claimed responsibility for the attack so far. But Taliban insurgents, who stepped up their attacks on Afghan and NATO-led troops since a rebel offensive was launched in May this year in the war-ravaged country, routinely claimed responsibility for attack on security forces.