Kabul, Afghanistan ? Peacekeepers in Afghanistan’s capital will take more security precautions because of a bus bombing that killed four soldiers, but the threat in Kabul is high and more attacks are likely, a peacekeeping official said Sunday.

German Lt. Col. Thomas Lobbering, spokesman for the International Security Assistance Force known as ISAF, stressed there had been no specific warning before Saturday’s attack.

A bomb-damaged bus that was carrying German peacekeepers is lifted from the roadside in Kabul, Afghanistan. A suicide attacker detonated a car bomb that killed four German peacekeepers and injured dozens of other people.

“Let’s make it absolutely clear that ISAF is here in Kabul because the situation is not yet stable and not yet 100 percent safe,” Lobbering said.

Four German soldiers were killed and 29 wounded in the blast, which occurred when a man driving a yellow taxi pulled up beside a bus carrying 33 peacekeepers in eastern Kabul and detonated between 220 to 1,110 pounds of explosives.

During the last few months, assailants have struck at peacekeepers with grenades, rockets and assault rifles in several separate incidents, but inflicted only light casualties until this weekend.

“The type of terrorist attacks and the amount of terrorist attacks is in line with what we have been expecting and what we still expect — I’m sorry to say that — for the upcoming future,” Lobbering said.

Saturday’s deaths were the first hostile fatalities on the multinational peacekeeping force since it was established to help maintain security in Kabul in December 2001.