A Palestinian security source said the three fighters were killed by an Israeli undercover unit while driving their car in the West Bank city of Jenin.
Late on Saturday night, troops returned to the Jenin refugee camp, sparking a fierce firefight with local fighters.
Palestinian officials said the 17-year-old girl, identified as Bushra Wahash, was shot by Israeli gunfire as she peered out the window of her home. The army was investigating the report.
The air strike was the first in the Gaza Strip since a ceasefire was agreed last November.
Police officer killed
A Palestinian policeman was also shot dead by Israeli troops operating in a village near Jenin, a Palestinian security source said.
Israeli forces had raided Kafr Dan looking for people it described as "wanted activists", Al Jazeera's correspondent reported.
|"Killing the Palestinian policeman means that Israel's escalation does not even rule out the Palestinian security services"|
Adnan al-Damiri, Jenin's police chief
Residents told Al Jazeera that Israeli snipers positioned on the occupied buildings opened fire at Abed.
His family said he was in the house at the time and unarmed. He was shot twice and died immediately, they said.
Israeli forces continued to carry out search operations in Kafr Dan and detained at least 10 people,.
Adnan al-Damiri, Jenin's police chief, accused the Israeli army of targeting its officers and held it responsible for the ongoing escalation in Jenin.
"Killing the Palestinian policeman means that Israel's escalation does not even rule out the Palestinian security services," al-Damiri said.
Palestinian police consider the Israeli operation an attempt to obstruct its efforts to restore security in Jenin, he added.
In Gaza City, three explosive devices were set off in the American International School causing damage but no injuries, Palestinian security sources and witnesses said.
"A large number of masked gunmen attacked the school at dawn. They poured petrol all around and blew up several explosive devices and destroyed some of the premises," Rebhi Salem, the school's director, said.
|Three explosive devices were set off at the |
American International School [AFP]
The armed men said they were part of an al-Qaeda organisation operating in Gaza, he added.
The school is a private institution that is part of an association of "American Schools" in the Middle East. The curriculum stresses English as well as Arabic studies. None of the teachers are American and a US embassy official said the school has no connection to the US government.
Two members of staff were briefly abducted from the school in March 2006.
Source: Al Jazeera and agencies