Jerusalem ? A suicide bomber blew himself up on a bus in northern Israel during this morning’s rush hour, killing at least three people, officials said.

No official casualty toll was immediately available. But rescue workers reported three dead and 28 injured, according to Israeli radio stations. The 7 a.m. (11 p.m. CDT Tuesday) blast occurred at an intersection on a main east-west highway near the large Israeli Arab town of Um el-Fahm.

“We’re talking about suicide bomber that got on at nearby station and then blew himself up,” police commander Yaakov Borovski said.

The blast comes as Israelis and Palestinians were attempting to work out a Mideast cease-fire under the mediation of U.S. envoy Anthony Zinni. It was not immediately clear how the bombing would affect the talks, though in the past such attacks have led to the collapse of negotiations.

The bus was traveling from Tel Aviv to Nazareth, police said.