Spain's capital is grappling with the aftermath of violent unrest following the death of an African street vendor who had been running away from police.
The death, and the clashes between riot police and protesters that followed in a central Madrid neighbourhood, cast a spotlight on the situation of a large community of undocumented migrants.
Madrid mayor Manuela Carmena on Friday announced a "thorough investigation" into the death of the man.
According to city officials, he was treated for a cardio-respiratory arrest that happened an unspecified time after he escaped a police crackdown on informal street sales on Thursday.
Subsequent protests by hundreds of African migrants and Spanish residents degenerated into rioting.
Spain: The death of an African immigrant led to a violent protest in central Madrid late night, leaving at least twenty people injured. The man, a 35-year old Senegalese street vendor, was trying to escape from a police crack down, according to witnesses. 15-03-2018 pic.twitter.com/JOe33dsbxd— Rowan Van Dijk (@Lastkombo) March 16, 2018
Demonstrators burned plastic waste bins, blocking narrow streets and setting fire to a bank branch. An Associated Press reporter saw protesters throw stones at dozens of riot police officers.
Police said six people were arrested. According to the Madrid region's emergency services, 20 people were treated for minor injuries, including 16 police officers.
Migrants' associations identified the dead man as 35-year-old Mbame Ndiaye, a Senegalese who had lived in Spain for 14 years but had not been granted residency.
They accused police of playing a role in his death, but local police unions said it had nothing to do with the crackdown on street vendors.
Atu Baye, a fellow Senegalese migrant and neighbour of the dead man, said Mr Ndiaye often joined groups to sell wallets, bags or other products.
"There were extremist groups infiltrated who burnt things. The Senegalese are not breaking things or stealing, they are not hurting anyone," said Cheikh Ndiaye, the president of AISE, an association of Senegalese migrants in Spain.
— eⒶtps (@eatps_) March 15, 2018
A police union representative said officers patrolling the area tried to help the man while medical help arrived.
"Contrary to what is being said, the agents were trying to revive him," said Emiliano Herrero, secretary general in the Madrid police for CCOO, one of the main national labour unions.
Mr Herrero said the mayor's announcement of an investigation seemed to "cast a doubt over the work of a professional police body". He said the judiciary should investigate such matters.
"Street sales by a collective of people who are not given the chance to work are a social and political problem that needs to be solved by politicians and legislators," he said.
"It's very easy to put the blame on the weakest link."
Malick Gueye, a representative of the Madrid Hawkers and Tinkers Union, said the vendors face increasing police abuse.
Because most of them lack regular papers, they find it difficult to take matters to court, he said.
On Friday, riot police intervened again in Madrid's Lavapies neighbourhood to protect Senegalese diplomats who were being threatened by angry countrymen gathered to mourn the death of Mr Ndiaye.
Even as it sees increasing gentrification, the neighbourhood is home to large numbers of migrants from sub-Saharan Africa who are denied permission to work.
Nearly 29,000 crossed into Spain last year, taking a perilous trip by boat or crossing barbed-wired fences into two Spanish territories in northern Africa. That was more than double the previous year's figure.
So far this year, 3,976 people have reached Spanish soil or been rescued in waters separating Africa and Europe.
- Press Association & Digital Desk