Bodyguards of the Hamas health minister have exchanged fire with gunmen at the health ministry in Gaza City.
Hamas gunmen were summoned to assist the health minister
Three people were injured in the confrontation. It seems the gunmen were seeking better treatment for a hospital patient, a BBC correspondent says.
Although it appears this was not an overtly political matter, the clash comes at a time of tension in Gaza.
On Sunday Fatah party supporters staged shows of strength, following clashes with Hamas supporters on Saturday.
A power struggle has been growing between the two rival groups. Although Hamas has just taken control of the government the presidency is still in Fatah's hands.
Hamas and Fatah representatives held talks late into Saturday night to try to resolve some of the differences.
But despite their calls for calm, protests by Fatah supporters continued on Sunday:
- More than 4,000 Palestinian security officers and Fatah supporters marched in the West Bank town of Jenin
- At least 20 Fatah-linked gunmen briefly took over the municipal headquarters in Nablus in the West Bank, forcing workers to leave.
People inside the health ministry on Sunday said the armed intruders were linked to one of the military wings of the Fatah party, though AP news agency says Fatah officials deny this.
The men arrived to complain to Health Minister Basim Naim about the treatment of a patient in one of Gaza's hospitals.
Tensions between Fatah and Hamas have surged
It is reported that he summoned Hamas bodyguards, and the two groups briefly exchanged fire. One of the victims was critically hurt after being shot in the chest while the other two suffered leg and hand wounds, reported the AFP news agency.
The Hamas gunmen then arrested a number of the intruders, chasing the others away.
"The time has passed when our institutions and our police can be attacked," Reuters quoted a spokesman for the interior ministry, Khaled Abu Hillel, as saying.
"Whoever holds a gun against one of our institutions, or one of our policemen, opens himself for death," he said.
The clash comes a day after Mr Naim said he was cutting the health budget amid a severe financial crisis which has gripped the Hamas-led government since it took office last month. Western nations have frozen aid.
Tension between the two factions were exacerbated when the exiled head of Hamas' political wing, Khaled Meshaal, accused President Mahmoud Abbas of plotting to overthrow the Hamas-led cabinet, sparking angry demonstrations.
Mr Abbas has overturned Hamas efforts to set up a new Gaza security force.