More than 20 people were killed and scores were wounded Thursday when three bombs ripped through a crowded market in a predominately Shiite neighborhood, an attack likely to inflame ethnic tensions in a country struggling with an upswing in violence.

The attack, the worst in Baghdad in several months, comes on a day that saw bombings across central Iraq, including the killing of a U.S. citizen riding in a diplomatic convoy.

State Department officials said Stephen Everhart, an international finance expert working with the U.S. Agency for International Development, was killed when his convey hit a roadside bomb while leaving a university in Baghdad.

Another U.S. citizen and two other people were injured, according to the State Department.

In a statement condemning what it called a terrorist attack against a U.S. citizen, the State Department said Everhart was in Iraq to try to bolster the country’s Ministry of Higher Education. He was an associate dean at the American University in Cairo, the Associated Press reported, and his biography on the university’s Web site says he was previously managing director of OPIC, the Overseas Private Investment Corp., in Washington.

Everhart’s sister, Michelle Everhart McDowell, said Everhart had lived in the District on and off before taking the American University job. He was married and had two daughters and a son, she said.

“He was just a wonderful person and dedicated to education,” Everhart McDowell said Thursday night in a phone interview from Columbia, S.C., where Everhart grew up. “He was just trying to do a good thing and it went bad. He doesn’t deserve this — it’s a horrible ending to a young life.”

In the Baghdad market bombing, several men reportedly wheeled in explosives on produce carts about 7 p.m.

Iraqi security officials said the attack in the Al-Shurta neighborhood, once largely controlled by Shiite cleric Moqtada al-Sadr’s Mahdi Army militia, occurred as the market was packed with evening shoppers.

At least 21 people were killed and more than 107 people wounded, security officials said. Officials said the death toll was expected to rise.

The attack comes a few days before hundreds of thousands of Shiites are expected to make an annual pilgrimage into Baghdad to visit the burial site of a revered religious figure.

In a separate attack Thursday evening, at least two people were killed and 10 were wounded in Dora, a predominately Shiite Baghdad suburb, when a car bomb exploded in a busy commercial district.

In all, the Baghdad region has been hit with at least two dozen explosions this week, including roadside bombs that appear to be increasingly targeting conveys carrying foreigners.

On Monday, a vehicle belonging to the French Embassy hit a roadside bomb in Baghdad’s Karrada neighborhood. No French officials were injured in that attack, but it marked the second time in a month that a French Embassy convoy had struck a roadside bomb.

On Wednesday, also in Karrada, a gunman opened fire on a convoy carrying a delegation of Iranian oil executives. Two bodyguards were wounded.

Special correspondent Aziz Majeed contributed to this report.