Merseyside Polices say missiles were thrown towards officers after an “initially peaceful protest”.
Protesters have clashed with police outside a hotel that provides refuge for asylum seekers on Merseyside.
Videos posted on social media show large groups of people gathered near the Suites Hotel in Prescot along with footage of a police van on fire.
Merseyside Police said officers had been dealing with what they described as an “initially peaceful protest and counter protest” on Ribblers Lane.
The force said missiles had been thrown and police vehicles damaged.
The protest is believed to have been sparked by a video, filmed near the hotel, on social media.
A police spokesperson said officers arrived at about 18:30 GMT.
“Officers were facilitating an initially peaceful protest and counter protest on Ribblers Lane,” the spokesperson said.
“During the evening, missiles have reportedly been thrown and damage caused to a police vehicle. No injuries have been reported at this time.
“Additional officers are in the area to deal with these incidents.”
Police have implemented a number of road closures on the East Lancs Road and are urging motorists to avoid the area and those in the area to disperse.
Knowsley MP Sir George Howarth has called for calm, saying: “I have referred an alleged incident posted on social media, which has triggered a demonstration outside the Suites Hotel, to Merseyside Police and Knowsley Council.
“Until the police have investigated the matter, it is too soon to jump to conclusions and the effort on the part of some to inflame the situation is emphatically wrong.”
Sir George added: “Those demonstrating against refugees at this protest tonight do not represent this community.”