An unidentified man attacked three people with a knife at an east London underground station on Saturday, before he was detained by the police. One of the victims was seriously injured, while the others sustained minor wounds, Reuters reported. The officers were called in after someone at the Leytonstone station sent them a distress message. The attacker had to be subdued with a stun gun, the police said.

"We are treating this as a terrorist incident," said Richard Walton, the head of the city’s Counter Terrorism Squad,in a brief statement. While a local newspaper had reported that the man had screamed “this is for Syria”, before attacking, the police did not confirm this. The country is on the second-highest alert level of “severe”, fearing attacks by militant group ISIS. On Wednedsay, members of the British Parliament voted to bomb ISIS targets in Syria. The air force has since carried out two strikes.