A major road was closed in Cardiff city centre following a double stabbing.
Both men, aged 21, are being treated in hospital for puncture wounds following the attack on Kingsway in the early hours of Sunday morning. They are in a stable condition.
According to detectives, a group of males were seen running away from the scene at around 1am.
A police cordon was in place between the junctions with Castle Street and Greyfriars Road while investigations continued during Sunday.
It's the second such attack in Cardiff this weekend, after an 18 year-old man was stabbed on Callaghan Square at around 3am on Saturday. Two men and a women were arrested.
But South Wales Police believe the two incidents are not linked.
Detective Inspector Matthew Cox said: ''We are investigating another serious assault in Cardiff city centre. On this occasion, two men were injured but thankfully both are currently in a stable condition.''
''We have a team of officers working hard to identify who was responsible...our officers are patrolling the city centre and are exercising stop and search powers when they have grounds to do so.''
Anyone who witnessed the attack or may have dash cam or phone footage of the attack should call 101, quoting reference no. 303953.