Forces loyal to Hamas and Fatah fought street and rooftop gun battles across Gaza on Sunday. Gunmen also fired mortars at President Mahmoud Abbas's offices while his forces seized two Hamas ministries. Abbas was not in Gaza at the time.
At least three people were killed and 20 wounded.
The ceasefire pact calls for an end to incitement through media channels such as radio and a stop to all demonstrations and rallies.
It also urges the holding of meetings to discuss important issues and calls upon all Palestinian factions to address the question of a national unity government.
Ibrahim Abu Najja, head of a high-level committee that includes all the groups, told AFP: "There is an agreement between all armed Palestinian groups for a ceasefire and to end the violence."
The development was confirmed by Ismail Radwan, Hamas spokesman, who told AFP that the ceasefire pact stipulates that "armed men must stop circulating on the streets".
Just before the news of the truce broke, a Fatah spokesman said a colonel in the Palestinian national security service belonging to Fatah was kidnapped and killed on Sunday in the Gaza Strip by Hamas fighters.
Adnan Rhami, 40, was abducted with two bodyguards while driving in the Jabalya camp, after which the masked kidnappers shot him and dumped his body near a hospital, the spokesman said.
It is not known what happened to the bodyguards.
The incident came during a day of violent clashes between Fatah and Hamas supporters after Abbas called for presidential and parliamentary elections to break a political impasse in the Palestinian territories.
Earlier on Sunday, a 19-year-old Palestinian woman was killed after supporters of Abbas's Fatah faction and Hamas clashed outside the presidential compound in Gaza City.
The death was the first civilian casualty since Abbas said the day before he was calling elections to try to end months of impasse during Hamas's rule.
Al Jazeera's correspondent Noura Odeh said a number of mortars had been fired at Abbas's city office.
The fighting came after the ruling Hamas party acccused Fatah of trying to kill the Palestinian foreign minister after shots were earlier fired at his convoy in Gaza City.
Mahmoud al-Zahar was unharmed in the attack.
|"The government rejects the call for legislative elections as they are unconstitutional and create confusion" |
Palestinian Prime Minister
Despite the violence, Abbas has indicated he is determined to push ahead with his plan to dissolve the government and hold early elections.
Ismail Haniya, the Palestinian prime minister, said Hamas would boycott the polls and accused the president of trying to topple the government illegally.
Haniya told a cabinet meeting that the call for early elections was "unconstitutional" and could create further disorder in the Palestinian territories.
"The government rejects the call for legislative elections as they are unconstitutional and create confusion," he said.
Earlier on Sunday, in an attack blamed on Hamas, dozens of gunmen raided a presidential guard training camp, killing a member of the elite force.
Palestinian presidential security sources said dozens of Hamas's al-Qassam Brigades members stormed the training centre in Shaikh Ijleen district, south Gaza City, firing mortar shells and rocket-propelled grenades.
|Supporters of Fatah and|
Hamas clashed in Gaza
Al-Qassam Brigades, Hamas's military wing, however, denied responsibility for the attack.
The latest clashes came after at least 18 Palestinians were wounded in fighting on Saturday after Abbas appeared on television to make his call for early elections.
Abbas said he decided to call for early presidential and parliamentary elections to resolve the unprecedented political crisis with Hamas, the ruling party.
On Sunday, he met members of the Central Election Commission to discuss a possible date for the vote.
"The message of the meeting is that he is serious, that he is saying 'don't doubt my words'." Palestinian spokesman Saeb Erekat said of Abbas. Erekat said he believed elections would be held around June.
The head of the panel said it would take at least three months to prepare new presidential and parliamentary elections.
Abbas has said in the past he would not seek another term has president - he was elected to a four-year term in a separate 2005 presidential vote - if early presidential elections are held Fatah is expected to ask him to stand again.
"For sure, Fatah is going to name Abu Mazen as the candidate for the presidential election, Nabil Shaath, a member of the party's Central Committee, said. "When we told him, he only laughed."
The Central Committee has the authority to choose the party's presidential candidate.