Palestinians gather around a destroyed Hamas base after it was hit during an Israeli missile strike in Gaza City. Israeli forces attacked Hamas targets Thursday in Gaza City, sending a large plume of smoke into the air. There were no serious injuries from the attacks.

Nablus, West Bank ? Israel rounded up a Palestinian Cabinet minister and 32 other Hamas leaders before dawn Thursday in the West Bank, trying a new tactic in its campaign to pressure the Islamic militant group into halting rocket barrages from the Gaza Strip.

The Palestinian president condemned the arrests, saying they would hinder his efforts to restore a truce with Israel, and Washington expressed concern about the detentions. Hamas threatened to retaliate with attacks inside the Jewish state.

The arrests reflected an Israeli decision to target the Hamas political leadership – but not necessarily with the lethal airstrikes it has staged over the past week on targets linked to the Hamas military arm.

Israeli aircraft continued attacks during the day and into the night, mainly on Hamas training bases and command posts. A huge plume of black smoke rose over Gaza City after an afternoon attack, but there were no serious injuries, Palestinian medics said.

During the night, a series of air raids injured nine Palestinians, including three children and two women, hospital officials said.

Just before midnight, an Israeli missile targeted a shack in the Shati refugee camp where Prime Minister Ismail Haniyeh of Hamas lives, but no one was hurt, Palestinian security said. Haniyeh went to inspect the site, but guards pulled him away because aircraft were still in the sky, officials said. Israel’s military said the structure was being used by Hamas and Haniyeh was not the target.

Israeli airstrikes also hit a money changer’s shop in Gaza City and a Hamas post in northern Gaza, Palestinian security said.

Earlier, at sundown, two mortar shells fired from Gaza exploded at Erez, the main crossing for people between the Palestinian territory and Israel. No was hurt, but there was considerable damage to two of the processing lanes, and Israel closed the crossing, the military said.

More than 40 Palestinians died in Israeli air raids during the past 10 days, and a rocket killed an Israeli woman Monday. The rocket barrages have severely disrupted life in the southern Israel area near Gaza, and thousands of frightened residents have fled.

Israeli Defense Minister Amir Peretz said the arrests in the West Bank were part of Israel’s attempt to neutralize Hamas and lessen the bloodshed.

“Arrests are better than shooting,” he told Israeli Army Radio. “The arrest of these Hamas leaders sends a message to the military organizations that we demand that this (rocket) firing stop.”