Baghdad, Iraq ? Gunmen kidnapped a group of people in the parking lot of a bus station on Wednesday and killed 22 of them, according to Iraqi police and military officials. The execution-style slayings occurred on the same day Defense Secretary Donald Rumsfeld visited Iraq and stressed the need to stem the sectarian violence that has killed scores of civilians in recent days.

The early morning raid took place in Muqdadiyah, about 60 miles northeast of Baghdad. The Iraqi military said four people were rescued but that the other captives had been killed by the time Iraqi soldiers arrived.

The attack was the deadliest single incident on a day when at least 45 people were killed by bombings, slayings and gunfire throughout Iraq. Wednesday was the fourth day of intensified sectarian killings that began Sunday when Shiite militiamen raided a Sunni Arab neighborhood in Baghdad and killed at least 50 residents.

Rumsfeld, in Iraq for a day-long visit, and Army Gen. George W. Casey Jr., the top U.S. commander in Iraq, said U.S. and allied forces in the country were focusing on ways to reduce sectarian fighting. Both said the best solution would be a combination of stronger Iraqi security forces and more robust political efforts to bring the country’s factions together.

Casey expressed concern about the rise of death squads targeting civilians on the streets. Although some of the recent violence, Casey said, is a backlash by Sunni insurgents “trying to demonstrate that they are still relevant” after the killing of Abu Musab al-Zarqawi, leader of the group al-Qaida in Iraq, “what we are seeing now as a counter to that is death squads, primarily from Shia extremist groups that are retaliating against civilians.”

Casey said more U.S. troops might be needed in Baghdad to combat the violence.