A explosion that police said was caused by a suicide bomber killed 20 people and wounded 18 more on a minibus in northern Baghdad today.
Some sources said there was more than one explosion.
The attack took place in the Shaab district of the capital, an area with a mixed population of Sunni Arabs, Shias, ethnic Kurds and others in northern Baghdad.
Meanwhile Iraqi officials said US forces killed up to six people in a raid on a Shia neighbourhood in west Baghdad late today, but the US military declined to confirm any operation in the city.
An interior ministry source said six people were killed and three wounded in the raid, which the source described as an airstrike.
Sources at Baghdad police headquarters said five were killed and 15 wounded in the attack on the Shula district, a rare Shia enclave in the mainly Sunni west of the capital.
Elsewhere, gunmen killed at least 10 people - including a television cameraman, a city councilman and a Sunni sheik - in executions and assassinations around Iraq.
Hours earlier, a cameraman for Iraq's independent Al-Sharqiyah satellite television broadcaster, was gunned down leaving his home in the northern city of Mosul. His wife was wounded, police said.
At least 89 journalists have been killed in Iraq since hostilities began in March 2003, according to an Associated Press count based on statistics kept by the New York-based Committee to Protect Journalists.
Another 35 media employees - including drivers, interpreters and guards, have been killed - all but one of them Iraqi.
Today's attack came the day after a suicide bomber killed 35 police recruits in Baghdad in one of the most deadly attacks on security force recruits in months.