May 29 (Reuters) - Following are security developments in Iraq at 1400 GMT on Tuesday: BAGHDAD - At least 23 people were killed and 68 others wounded when a powerful bomb in a parked bus exploded in central Baghdad, police said. BAGHDAD - At least 18 people were killed and 41 wounded when a car bomb exploded in a busy market of a mainly Shi'ite neighbourhood in southwestern Baghdad, police said. BAGHDAD - Gunmen abducted a group of Westerners from inside a Finance Ministry building in Baghdad, police and a witness said. The witness said three computer experts and several bodyguards were seized. Police said four people were taken hostage and identified the experts as German nationals. DIYALA PROVINCE - Six U.S. soldiers were killed on Monday after explosions targeted their vehicles in the volatile Diyala Province, the U.S. military said. DIYALA PROVINCE - Two U.S. soldiers were killed when their helicopter went down in Diyala Province on Monday, the U.S. military said. BAQUBA - The bodies of 21 people were found shot dead in two different districts of Baquba, 65 km (40 miles) north of Baghdad, police said. SUWAYRA - Police retrieved the bodies of five men, two of whom were decapitated, from the Tigris river in the town of Suwayra, 40 km south of Baghdad, police said. SHIRQAT - Gunmen killed two policemen and wounded three in the town of Shirqat, 80 km south of Mosul, police said. SHIRQAT - A roadside bomb targeting a police patrol killed two policemen and wounded three others on Monday in Shirqat, police said. KIRKUK - Gunmen killed Mahmoud Hakim Mustafa, the editor-in-chief of Hawadith weekly newspaper, on Monday near his home in the northern city of Kirkuk, 250 km north of Baghdad, police said. BAGHDAD - U.S. forces detained 14 suspected insurgents, including the suspected al-Qaeda leader of a violent western Baghdad neighbourhood, during operations in the capital, Mosul and Taji, the U.S. military said.