Israeli troops opened fire on a crowd of protesters at another border crossing several hours later. A Gaza health official said a 22-year-old man was killed and 16 people, including three children, were wounded. The military said it opened fire after spotting gunmen in the crowd, including one carrying an anti-tank missile.

Two militant Palestinian factions _ Islamic Jihad and the Al Aqsa Martyrs' Brigades _ claimed responsibility for the bombing at the Erez passenger crossing, which could be heard for miles around and shattered windows in Netiv Haasara, an Israeli community across the border.

Abu Ahmad, an Islamic Jihad spokesman, said the bombing was meant to "send a message" to Israel that if it didn't accept a truce, "Gaza is not going to be a place where you will enjoy stability."

Ibrahim Nasser, a 23-year-old Islamic Jihad militant, drove the truck filled with at least four tons of explosives into the crossing in northern Gaza, spokesmen for the militant groups said.

The truck exploded on the Gaza side of the border, blowing a hole in a pedestrian passageway leading out of the terminal and into Gaza. No pedestrians were at the crossing at the time because it was early, and the Israeli military said no soldiers were wounded.

Abu Thaer, a spokesman for Al Aqsa, said three other fighters on the mission were following in a jeep, and planned to enter the crossing after the explosion to spray the area with gunfire. He said they fled after their jeep ran into a mound of sand and overturned.

In terms of the amount of explosives used, Thursday's attack was the biggest since Israel pulled its settlers and troops out of Gaza nearly three years ago, Israeli military spokeswoman Maj. Avital Leibovich said.

Israel's army regularly clashes with Gaza gunmen who fire rockets at Israeli towns and attack troops along the border. The crossings, which militants see as hated symbols of Israeli authority, are frequent targets.

Since June 2007, when Hamas came to power, Israel and Egypt have kept the Gaza crossings closed to everything but humanitarian aid in an attempt to weaken the group. The sanctions have been tightened in response to the ongoing rocket fire.

The Erez crossing will be closed until the damage can be repaired, said Israeli military spokesman Peter Lerner. Erez is the main crossing point for international aid workers and Palestinians traveling to Israel for medical treatment, he said, and thus "the main victims of this attack are the Palestinians themselves."

But a U.N. official warned Israel not to let such attacks halt the flow of goods into Gaza.

"If you hand the agenda over to the extremists, then they are very happy about it. If it only takes one rocket to derail everything, then that's massive power," said John Ging, the Gaza director of the U.N. organization in charge of Palestinian refugees.

Hours after the suicide bombing attempt, thousands of Gaza protesters gathered about five miles away at the Karni cargo crossing to demand an end to the Israeli blockade.

"You will fall, your corrupt state will fall!" the crowd at the crossing chanted. Some of the protesters climbed poles to hoist Hamas flags, and pro-Hamas songs played in the background.

Israeli tanks rumbled into Gaza from the Israeli side of the passage, and Israeli bulldozers leveled farmland in the area so militants couldn't hide. Plumes of black smoke climbed into the sky after protesters set tires afire.

Gunshots pierced the air at the crossing, and Israeli troops fired tear gas to keep the protesters at bay. Dr. Moaiya Hassanain of the Gaza Health Ministry said a 22-year-old man was shot to death after troops opened fire, wounding 16 others.

Separately, a 62-year-old Palestinian civilian was shot and killed in central Gaza on Thursday morning, Hassanain said. The military said it had no forces in the vicinity and the circumstances of the man's death remained unclear.