Belgian police have arrested a man who injured three people on a metro train at the Brussels Schumann station on Monday, Reuters reports.

Knife attack in Brussels subwayPhoto: / Shutterstock editors / Profimedia

Although the motive for the attack remains unclear, police are ruling out terrorism, prosecutors said, confirming the arrest of a 30-year-old man.

A source close to the investigation told Reuters that the attacker was previously known to the police.

“Cooperation with various federal police services and (local police) ensured the swift apprehension of the criminal,” Brussels Mayor Philippe Clouse wrote on Twitter.

The attack happened at 5:45 p.m. local time in a subway car as it arrived at Schumann station, which is known to be crowded during rush hour.

One of the victims is in serious condition, all three are in hospital.