Updated

A rocket fired from the Gaza Strip struck Israel on Tuesday as tensions are mounting in the region weeks ahead of President Barack Obama's visit.

Militants claiming affiliation with Palestinian President Mahmoud Abbas' Fatah movement took responsibility for the attack, saying they fired the rocket to avenge the death of a Palestinian in Israeli custody.

The detainee, Arafat Jaradat, 30, died over the weekend after interrogation by Israel's Shin Bet security services. Palestinian officials, citing an autopsy, said the detainee was tortured, while Israel says more tests are needed to determine the cause of death.

Jaradat's death sparked protests in the West Bank, including near the town of Bethlehem on Monday.

Two Palestinian teens, ages 13 and 16, were wounded in a confrontation with Israeli soldiers. The older boy was transferred to Jerusalem's Hadassah Hospital after being shot in the head and was in critical condition Tuesday, breathing through a respirator, officials said.

In the West Bank, Abbas on Tuesday accused the Israeli military of using increasingly harsh methods to clamp down on Palestinian rock-throwing protests.

"We don't want tensions. We don't want escalation," Abbas said, rejecting recent allegations by Israeli officials that he was stoking tensions for political gains.

The rocket from Gaza landed south of the Israeli city of Ashkelon early Tuesday, said police spokesman Micky Rosenfeld. The rocket caused damage to a road, but no injuries, he said.

It was the first rocket fired from Gaza since Israel's last major military offensive against rocket squads in the coastal strip last November. The Hamas militant group has ruled Gaza since ousting forces loyal to Abbas in 2007.

Over the past decade, Gaza militants have fired thousands of short-range rockets and mortar shells at Israel, and Israel has responded with military strikes. In between periods of cross-border violence, informal cease-fires have taken hold.

In an email sent to reporters, militants claiming affiliation with Fatah's violent offshoot, the Al Aqsa Martyrs' Brigades, said they fired the rocket to avenge Jaradat, the detainee who died in Israeli custody. It was impossible to verify the claim. The Fatah-allied militant group has kept a low profile since the Hamas takeover.

Hamas government spokesman Ehab Ghussein denied a rocket was fired, indicating the Islamic militant group was trying to distance itself from the incident. In the past, militant splinter groups have fired rockets at times when Hamas tried to discourage such attacks.

Hamas has carefully enforced an Egyptian-brokered cease-fire that ended eight days of heavy fighting with Israel in November. Israel's army had no immediate comment.

In the West Bank, there has been an increase in clashes between Palestinian stone throwers and Israeli troops in recent weeks.

In Monday evening's confrontation near Bethlehem, the Israeli military said protesters threw "improvised hand grenades" at a Jewish shrine in the area, endangering worshippers inside.

Soldiers fired at the legs of a Palestinian throwing grenades, lightly wounding him, the military said. Later, soldiers fired rubber-coated steel pellets at demonstrators, seriously wounding one who was taken to an Israeli hospital, the official said.

Palestinian medical officials said two Palestinians, ages 13 and 16, were seriously wounded by live fire. The 13-year-old was wounded in the abdomen and the older boy in the head, the officials said.