French troops in the Central African Republic have clashed with rebels they are trying to disarm in a bid to end violence between rival armed groups which has killed hundreds of people since last week.
Shooting erupted on Monday near the airport as the troops searched for weapons in the capital Bangui, according to the Reuters news agency.
French forces later came under attack by former rebels in the city centre but there were no reports of casualties.
A top Seleka commander, Nourdine Adam, was taken into custody following the clashes.
"Nourdine Adam was taken into custody and transferred to the airport's international military base, after an altercation on a road with local residents," Al Jazeera's Nazanine Moshiri said on Monday. "He stayed there for a while, but he was later seen at the Presidential Palace."
"We don't know whether he was picked up by the French as part of their disarmament drive, or for his own safety," Moshiri added.
The violence in the former French colony is between the mainly Muslim Seleka rebels - originally from neighbouring Chad and Sudan - and the Christian anti-Balaka whose name means "machete", the weapon of choice for Seleka.
The United States on Monday offered logistical support and said that it would provide military transport planes to carry Burundian troops to the country to join up with a 2,500-strong African Union peacekeeping force.
Seleka rebels seized power in March and installed Michel Djotodia as president, the first Muslim leader in the predominantly Christian nation.
Both militias are blamed by rights groups for committing atrocities such as rape and for the massacre of civilians. At least 459 people have been killed in Bangui alone since Thursday, according to Red Cross officials.
'No easy job'
France said it was prepared to use force if fighters rejected calls to disarm or return to barracks. Some 1,600 French troops are in CAR, alongside the African troops who were earlier deployed to try to end the violence.
The deployment gained momentum after a resolution sponsored by France was passed last week to pave the way for military action. The troops have the mandate to use "appropriate measures" to protect civilians.
"This is not an easy job, but our soldiers are well prepared," Laurent Fabius, France's foreign minister, told France Inter radio.
The order to disarm had been broadcast on local radio in Bangui and "if that is not enough, force is going to be employed."
In an early test of France's resolve, its troops traded fire with gunmen near the airport Monday morning. A French army spokesman in Paris called the incident "insignificant".
"Many armed elements who held positions in Bangui have left their positions to go back to their barracks," Colonel Gilles Jaron said.
However, French troops again came under attack later in the day in the PK 5 neighbourhood from suspected Seleka fighters.
It was not clear whether there had been casualties in the two incidents.
After the gun battle at the airport French forces arrested some of the Seleka fighters, Al Jazeera witnesses said.
As French forces manned checkpoints and patrolled the streets, pockets of crowd violence erupted in several districts.
In the Castor neighbourhood, a Reuters reporter watched as a crowd attacked a man they accused of being a disarmed Seleka fighter after French soldiers removed weapons from a house there, then left.
At a mosque in the PK 5 neighbourhood, the resident imam showed journalists the bodies of two men who he said had been beaten to death by Christians.
The arrival of French troops has been broadly welcomed in a city still struggling to emerge from a period that saw both Seleka fighters and Balaka rebels go door-to-door killing civilians as they cowered inside.