Two teenage boys have been charged with murder after a "chance meeting" led to a 20-year-old man being fatally stabbed in Logan, south of Brisbane, in the early hours of Friday.

Police arrested and charged the 15-year-old and 16-year-old overnight.

Both are facing murder charges, while one has also been charged with failing to provide access to a phone and the other is charged with possessing a small amount of cannabis.

Bail was denied for both boys, and they are expected to face the Brisbane's Children's Court.

Detective Superintendent Brendan Smith said the accused are not known to the victim.

"Two groups of youths have come together, a clash has occurred, and now we've got one person who has been killed," he said.

"It was a chance meeting with young people.

"You can only imagine the impact on his family and friends."

In relation to those charged, "you've got two very young people who are going to be impacted for the rest of their lives," he said.

Detective Superintendent Smith said young people should not carry knives.

"There is no valid reason to carry a knife, I don't care what anyone says," he said.

"It's a millimetre either way between life and death."

Police are seeking public assistance in tracking the movements of a car involved — a black Audi with the registration 448-GF5, with the front numberplate on an angle.