Israeli tanks entered the Rafah refugee camp (search) on the Gaza-Egypt border early Friday, residents and Palestinian security officials said. There were heavy exchanges of fire between soldiers and Palestinian gunmen, they said.

Soldiers took over the rooftops of three buildings and used them as positions for sharpshooters to keep the gunmen away, witnesses said.

Ambulances were sent to the scene, but there were no reports of casualties.

The Israeli military had no immediate comment.

The Rafah camp is a frequent focus of clashes, as Israeli forces enter to look for tunnels under the border they say are used by the Palestinians to smuggle in weapons from Egypt. The Israelis often destroy buildings used to cover the entrances to tunnels, and hundreds of Palestinians have been left homeless in previous operations during more than three years of Palestinian-Israeli violence.