Police believe aspects of the disturbances at Europe's largest immigrant detention centre in Britain may have been orchestrated.
Firefighters are still trying to put out a blaze at the Yarl's Wood immigrant-holding centre on a former military base in Bedfordshire, around 40 miles north of London. The buildings were evacuated and five people were taken to hospital.
A number of missiles were also thrown as emergency services arrived at the centre near Bedford.
The fire is believed to have been started after trouble broke out between staff and some of the around 400 detainees. Media reports have said it started after a riot over treatment of a female detainee.
Officers told a press conference seven male and one female asylum seeker are now in custody.
They were picked up close to the centre and it is not yet known if others are missing.
Deputy Chief Constable Cliff Dixon says police are still unsure how a number of asylum seekers managed to escape from the centre and that there are conflicting reports about what may have started the incident.
Meanwhile the UN refugee agency reacted to the news of the fire by reaffirmed its opposition to the detention of asylum seekers.
Mr Kris Janowski, spokesman for the UN High Commissioner for Refugees (UNHCR), said the agency was especially worried about the grouping together of asylum seekers whose claims have been rejected with those whose applications are still pending.
He said the practice was a "recipe for problems" as had been seen in Australia, whose hardline policy towards asylum seekers has brought it under the international spotlight recently.
But he noted Britain only detains a small proportion of asylum seekers and has no policy of mandatory detention of unauthorised asylum seekers though he said numbers of those detained were increasing.
PA and AFP