FACTBOX: Security developments in Gaza, May 17

May 17 - The following are security developments in and around Gaza as of 2300 GMT on Thursday:

Asterisk denotes new or updated entry.

GAZA - Israeli aircraft strikes a Gaza City building that housed Hamas's Executive Force. At least 40 people are wounded, hospital officials say.

GAZA - A second air strike hits a car carrying a senior commander in Hamas's armed wing. He is seriously wounded and another militant in the vehicle is killed.

GAZA - A third Israeli air attack hits an Executive Force position outside the home of the Interior Ministry's spokesman. A Hamas militant is killed.

GAZA - A fourth air strike targets a rocket-launching crew in southern Gaza, but hospital officials say two civilians are killed -- two teenage brothers -- and three others wounded.

* GAZA - A fifth air strike hits a training base for Hamas's armed wing in the Zeitoun area east of Gaza City, close to the border with Israel. A Hamas official and police sources say there are at least two dead and five wounded but medical crews are having trouble reaching the scene to make an accurate assessment. Fighters were stationed there to counter any Israeli ground raid. The Israeli military said it "attacked a structure" in the Gaza Strip.

GAZA - At least four Palestinians are killed in internal fighting between Hamas Islamists and President Mahmoud Abbas's secular Fatah faction.

SDEROT, Israel - Busloads of Israelis pour out of the southern Israeli town of Sderot to escape a barrage of rockets fired from the nearby Gaza Strip. Israeli Prime Minister Ehud Olmert visited the town and assured residents of the government's solidarity and readiness to reduce attacks.

SDEROT, Israel - At least two people are lightly wounded in an early morning rocket salvo in Sderot, near the Gaza border. At the end of the day, a rocket hits a synagogue but causes no injuries, an Israeli military spokesman says, adding that it was about the 15th rocket fired on Thursday and the 90th in the past three days.

GAZA - Israeli army says it has sent a small force of troops, tanks and other armored vehicles into northern Gaza on a "defensive operation". Israeli army breaks into local radio broadcasts to warn northern Gaza residents not to approach Israeli forces operating in the area. Residents say they hear what they believe is two tank shells fired.

ISRAEL/GAZA BORDER - Israel deploys artillery along its border with Gaza.