KABUL, Afghanistan — Suicide bombers struck a busy market Wednesday in southern Afghanistan, killing 22 people and injuring 50 others, President Hamid Karzai’s office said.

Karzai, who is on a visit to China, condemned the attack.

A first bomber on a motorcycle detonated his explosives near a restaurant in a busy market in Kandahar, according to Abdul Razaq, a provincial police chief. The market is crowded with civilians and truck drivers, most of them transporting NATO supplies.

When residents flooded the area after the first attack, a second bomber blew up his explosives in the crowd, causing more casualties, Razaq said.

The attacks occurred near the Kandahar airfield where NATO troops in the region are based.

Kandahar is the birthplace of the Taliban and has been the site of fierce fighting between international forces and insurgents.

In another incident overnight, a NATO airstrike killed 18 people in Logar province, said Sahib Khan, a provincial official.

Some of the victims were women and children, but it was unclear whether all the dead were civilians, Khan said.

NATO forces said the strike occurred when soldiers returned fire during a mission targeting a Taliban leader.

“While conducting a follow-on assessment, the security force discovered two women who had sustained nonlife-threatening injuries. The security force provided medical assistance and transported both women to an ISAF (International Security Assistance Force) medical facility for treatment,” a military statement said. “Multiple insurgents were killed and the Afghan and coalition security force seized several weapons and a quantity of explosives.”

— CNN’s Mohammed Jamjoom contributed to this report.