Gunmen opened fire on the house of Haiti's justice minister, killing a police officer in a brazen attack that underscored the country's shaky security climate ahead of key fall elections, officials said Wednesday.

The Tuesday night shooting in Port-au-Prince came days after U.N. peacekeepers and Haitian police raided two rural towns to remove armed ex-soldiers who helped oust former President Jean-Bertrand Aristide (search) last year. Two peacekeepers and two ex-soldiers died in clashes.

A group of gunmen fired several times at Justice Minister Bernard Gousse's (search) house in the capital, killing a policeman who was guarding the property, said Yollete Mengual, a spokeswoman for the interim government.

"This is a message from people who are unhappy with the fight against corruption, drug trafficking and kidnapping, people who are enemies of the law," Gousse told reporters. "My answer is that I'm not backing down."

The attack came as peacekeepers and interim authorities struggle to disarm street gangs and ex-soldiers blamed for hundreds of recent killings that many fear could spill over into elections in October and November.

On Tuesday, U.S. Defense Secretary Donald H. Rumsfeld (search) praised peacekeeping efforts in Haiti but raised doubts about the prospects for elections, citing the U.S. government's experience with ensuring the safety of voters in Afghanistan and Iraq.

"It takes a lot of efforts and planning from a security standpoint," Rumsfeld said en route to Brazil as part of a four-day swing through Latin America. "You simply have to be ahead of it or it can get bad fast."

U.N. envoy to Haiti Juan Gabriel Valdes said Tuesday the United Nations is willing to disarm gangs and help them return to civilian life, but is prepared to go after them "with firmness" if they refuse.