Riots across Britain triggered by false information online about a suspect in a recent knife attack have led to the arrest of about 380 people. Prime Minister Keir Starmer has warned that incitement of violence online will also be subject to criminal penalties, writes NHK World.

The unrest began after 3 children were fatally stabbed by a 17-year-old boy in Southport, England, on July 29. False information spread online claiming that the suspect was a Muslim immigrant who had arrived in the UK illegally by boat.

Protests against the government’s immigration policies erupted across Britain on the day after the incident, escalating into riots. A local mosque was attacked with bricks. On Sunday, protesters in Rotherham, England, tried to break into a hotel that housed asylum seekers. At least 12 police officers were injured as protesters threw bricks and other objects at them.

Local police said the protesters appeared to hold far-right and anti-immigration views. The National Police Chiefs’ Council announced on Monday that 378 people had been arrested in the past week, and that more arrests were expected as they identify those who were involved.

Also on Monday, Prime Minister Starmer condemned the riots, saying they were not protests but “pure violence”: “The full force of the law will be visited on all those who are identified as having taken part in these activities. I’ve been absolutely clear that the criminal law applies online as well as offline”.