It has been two months since Hamas raised its green banner over the Palestinian president's home in Gaza after forcing Fatah rivals to flee.

Hamas followed the rout by successfully forcing Gaza militants to free BBC reporter Alan Johnston after 114 days in captivity.

Powerful families were kept in check. Hamas police officers kept a lid on crime. And Fatah fighters quietly stewed in their homes.

Now the first fissures are starting to emerge and Hamas power is being challenged.

First, Hamas got into a skirmish with Islamic Jihad fighters. Then there was a kerfuffle at the main Gaza City hospital when a well-known official tried to organize a strike.

Over the weekend, Hamas broke up a wedding party and later said the men celebrating the happy event had been illegally firing weapons in the air.

The clash was captured on film and quickly posted on YouTube. The footage (below) shows Hamas forces zooming in on the wedding party and beating several men.

Today, Hamas fighters forcibly broke up a Fatah protest. Several hundred Fatah demonstrators tried to challenge a ban on demonstrations. Hamas beat several and confiscated video of the fighting.

It's clear that Hamas rivals are starting to test Hamas. And the group faces a difficult challenge in trying to impose order without resorting to heavy-handed tactics.

Human rights groups have documented sporadic cases of torture by Hamas. But, earlier this month, they seemed certain that these were isolated cases that would not become a pattern.

Just about the only thing Hamas has going for it right now is its ability to establish law-and-order in Gaza. Even Fatah supporters had to concede that Hamas had brought along a new era of safety in Gaza after they took over.

If Hamas loses its respect as the new rulers of Gaza, the group is likely to face more challenges. Instead of being cowed, Fatah and powerful Gaza familes are likely to be emboldened if Hamas goes too far.