A bomb exploded in a bus carrying German peacekeepers in Kabul on Saturday, killing at least six people on board and wounding about 11, police said. The International Security Assistance Force, or ISAF, bus was traveling from the airport toward eastern Kabul and driving near the city's customs house when the bomb exploded inside it, Kabul Police Chief Basir Salangi told The Associated Press. "Some foreign people have died and some have been injured," Salangi said. He said he believed five or six people had been killed and about 11 wounded. Gen. Abdul Raouf Taj, the police chief in District Nine of the Afghan capital, said he believed the bomb had exploded near the bus. Maj. Sarah Wood, an ISAF spokeswoman, said there were casualties aboard the bus, "some of which we believed are ISAF," but she wouldn't say who or how many. "Our priority is to get them medical assistance as soon as possible," she said. As she spoke, a large German military helicopter landed in the road near the site of the explosion and not far from the base that houses German and Dutch troops in Afghanistan. Police halted traffic and all pedestrians were stopped about 200 yards from the scene, allowing only ambulances and other emergency ISAF vehicles to roar past. Suspected Taliban fighters have been stepping up attacks on foreign forces this spring, particularly in the south and east of Afghanistan. About 11,500 coalition troops, the bulk of them Americans, have been deployed in Afghanistan since the Taliban government was overthrown in a U.S.-led war in 2001. **PHOTO CAPTION*** German soldiers from the International Security Assistance Force (ISAF) patrol the Butkhak district of southern Kabul where one of their comrades was killed and another injured when their vehicle went over a mine. (AFP/Shah Marai)