TAIBEH, Israel (AP) _ Palestinians threw grenades and fired shots early Thursday from an apartment in this Arab town north of Tel Aviv, Israel radio reported.

Israeli army radio reported that an undisclosed number of Palestinians were killed, but it was unclear exactly when the explosion occurred. Police refused to comment on the reports.

Israeli police surrounded the apartment building and used bullhorns to order residents to evacuate the area, Israel radio said.

A helicopter hovered above the building, and top police commanders rushed to the scene as well as agents from the Shin Bet security service, the report said.

No further details were immediately available, and it was not known if there were any injuries.