According Ynet coverage the burning seems to have been limited to tires outside the police station, and that's all that can be seen in their (embedded) video.
On Sunday a Hamas police officer shot dead a Gazan youth who was part of a group of civilians who stopped an aid truck trying to deliver packages. The young man belongs to the Abu Burika family, a large clan in southern Rafah, which was asked to assist Hamas in guarding the aid packages until a member of the family was shot. Following the incident, the family threatened to take revenge, burning tires outside the police station in the city.
"We call on the Hamas government to take responsibility for its actions. They told us to guarantee the entrance of the aid, but today they shot at us and a member of my family," said a member of the victim's family, during a protest outside the police station.
The death was even been reported by Xinhua, but without much detail. OTOH Xinhua claimed that both the police station and the aid center were set on fire.
A Palestinian man was killed and several others were wounded Sunday during clashes and chaos at a humanitarian aid distribution center in Rafah, southern Gaza Strip, Palestinian sources said.
The sources, who spoke on condition of anonymity, said the clashes erupted after hundreds of people rushed to the center, causing stampedes as security forces fired shots to disperse the crowd. They said the relatives of the slain man set fire to the center and a nearby police station and blocked roads with burning tires.
This (of Dec 25) was hardly the first aid-related stampede in Gaza though. Another was reported and even video'd Dec 17, but no casualties were reported then. Break-ins at aid centers in Gaza have been reported even in late October.
Some of the close-up footage of that Dec 17 event does show some armed people (presumably Hamas although there are some armed private security companies in Gaza--it's not clear if the latter ever guarded aid though) on top of some of the trucks, so armed guards/presence in such [later] events is also likely.
CNN has some footage of the stampede on Dec 25 (which they describe as a "brawl" and--somewhat sarcastically, I guess--as a "Christmas eve jam") and they report gunfire at that event.
Thus far I've not seen any visual confirmation of either the "police station" or the aid center burning, as Xinhua alleges happened. Sometimes fires in Gaza do get spotted from satellite, e.g. the NYT reported a water treatment plant burning a while back (mid Nov), but those satellite photos take some time to surface.