Beit Hanoun, Gaza Strip ? In the alley among the shell-damaged houses there were pools of blood and children’s shoes.

Stunned men sat against the pockmarked walls, speechless, and a throng of grieving women overflowed from a nearby house.

A barrage of Israeli artillery shells that crashed into a crowded neighborhood killed at least 18 people in this town early Wednesday, eight of them children, and wounded dozens more, most from the same extended family. It was the highest number of Palestinian civilians killed in a single strike since fighting erupted between Israelis and Palestinians six years ago.

The Israeli army said that the barrage was aimed at areas used by Palestinian militants to launch homemade rockets at Israel and that some of the shells had apparently gone off course. Defense Minister Amir Peretz ordered a halt to further shelling in Gaza and an immediate army inquiry.

Palestinian President Mahmoud Abbas called the shelling a massacre and said Israel would “bear the consequences.” Militants vowed swift revenge.

In Damascus, Khaled Mashal, the exiled leader of the militant group Hamas, called for renewed attacks on Israel by all Palestinian factions, saying a cease-fire had expired last year.

“The armed struggle is free to resume,” he said at a news conference. “Our condemnation will not only be with words, but deeds. The resistance doesn’t talk, it acts.”

Family members mourn the dead at the hospital morgue in the Gaza Strip town of Beit Lahiya. Israeli tank shells landed in a residential neighborhood north of the neighboring village of Beit Hanoun early Wednesday, killing at least 18 people in their sleep, including eight children, witnesses and hospital officials said.

The artillery barrage hit Beit Hanoun at dawn, when many people were still sleeping.

A shell hit the four-story apartment house of the Athamna family, crashing through the ceiling of a room where a group of children slept. A 6-month-old baby was killed, blown out of the window by the blast, and a schoolgirl was killed in the next room, neighbors said. Other children were wounded.

“I heard screaming, and then the people in the building took the wounded and rushed outside,” said Ahmad Abu Odeh, who lives across the street. “Then another shell landed among them. They were cut to shreds. Shells kept falling, and we couldn’t rescue them.”

The shells hit the Athamna house and also struck three neighboring homes, leaving dead and wounded on the street, many with limbs sliced off by shrapnel, witnesses said.

“It looked like a jungle, as if people had been torn apart by a wild animal,” said Muhammad Hamed, 35. “I picked up a hand. A man had been cut in half.”

“I saw a leg, a head,” said Ahmad Ashour, 23. “Not a single person was whole.”

Maj. Gen. Yoav Galant, the chief of Israel’s southern command, said that the shelling was aimed at an area about 500 yards away from the neighborhood and that a problem with the calibration of the army cannon may have caused the shells to miss their mark.

Galant said the artillery was directed at areas from which militants had launched rockets on Tuesday at the southern Israeli city of Ashkelon after warnings of further attacks. Four rockets hit Ashkelon on Tuesday, hours after the army ended a weeklong incursion in Beit Hanoun aimed at curbing rocket fire.

More than 50 Palestinians, both militants and civilians, were killed in the operation, which left much of Beit Hanoun in shambles.