A Palestinian was killed overnight by Israeli forces, as further violence continued in the Gaza Strip, medical sources said.
Clashes in Gaza have shattered a period of calm
A body - described on Israeli radio as a "Palestinian youngster", and on Palestinian radio as a "martyr" - was found in the al-Sejaiya neighbourhood.
Some reports said he was shot - others that he was hit by an artillery shell.
On Tuesday an Israeli soldier and four Palestinian militants were killed in clashes in the Gaza Strip.
The Israeli soldier died in what Hamas said was a booby-trapped chicken coop in central Gaza, which exploded during a search for weapons.
The militant group held a press conference, at which masked men said more than a ton of explosives had been packed into the trap.
The group said two of its fighters were killed in gun battles with Israeli forces following the explosion.
Soon after the attack, the Israeli army killed two militants from the Islamic Jihad group in a missile attack.
The army also moved temporarily into al-Sejaiya - where the body was found on Wednesday - a neighbourhood that is controlled by militants.
Hamas claimed to have set an elaborate trap
About 10 Palestinian civilians, at least four of them schoolchildren, were injured during the incursion, according to reports.
The renewed clashes come a month before Palestinians vote for a new leader of the Palestinian Authority on 9 January.
The BBC's Alan Johnston in Gaza says Israeli forces that occupy the Strip and defend Israeli settlements frequently come under attack, but there have been fewer such clashes in the weeks since Yasser Arafat died.
The flaring violence is thought to be the heaviest in Gaza since the death of the veteran Palestinian leader.