561 were arrested in the earlier riots (on Saturday.) There are photos at both links below; the availability of photos kind of surprises me:

Riyadh riots: Saudis call for no compromise on security
By Abdullah Al-Bargi in Jeddah & Mohammed Rasooldeen in Riyadh, Arab News, Nov. 11, 2013

Saudis have renewed support for the ongoing labor raids against illegals following the rampage in Riyadh by undocumented Ethiopians on Saturday.
The rioting, which left at least two dead and dozens injured, raised two pertinent questions for Saudis: How did illegals get in here and how did they manage to gain employment?
Late Saturday, hundreds of Ethiopians, including at least 70 women, armed themselves with knives, rocks and broken bottles and threatened police, pedestrians and motorists in Manfouha district’s narrow streets.
Anti-riot police fired in the air and used truncheons to break up the crowd.
In the ensuing clashes, two men were killed — a Saudi and an Ethiopian. The Saudi victim, 32, was struck on the head with a rock.
More than 70 people, including 28 Saudis, were injured and 104 vehicles were damaged.
Several shops were ransacked. Police arrested 561 people. The district’s schools remained shut on Sunday, according to eyewitnesses [....]

Sudanese killed as illegals riot again in Riyadh
By MD Rasoolden from Riyadh, Arab News, Nov. 14, 2013

Fresh violence erupted in Riyadh’s Manfouha district on Wednesday, resulting in the death of a Sudanese resident, police said.
At least 17 expatriate workers were also reported injured as they clashed with local residents.
Illegal migrants “rioted, hurling rocks at passersby and cars,” police said, before forces intervened and “controlled” the situation.
The protesters, mainly Africans, started harassing motorists and members of the public at Frayan Street in the southern part of Manfouha.
Police said they were still investigating what provoked the fresh violence, the second in district in five days. Last Saturday, security forces battled Ethiopian illegal workers who had gone on a rampage apparently in anger over an ongoing government crackdown against visa violators [....]