A man in his 40s is in a serious condition in hospital after being stabbed at Wynnum State School on Brisbane’s bayside.

The man was stabbed in the face, hands and back about 3:00pm, the Queensland Ambulance Service said.

The Queensland Police Service (QPS) said initial information was that two men who are known to each other became involved in an altercation in the school car park off Boxgrove Avenue around 2.45pm.

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One sustained stab wounds and was transported to the Princess Alexandra Hospital, QPS said in a statement.

A second man is assisting police with their inquiries, the statement said.

Neither of the men were believed to be employees of the school, it said.

Parent Michelle Hazel, whose son is a year four student at the school, said she saw a man being treated by paramedics in the car park.

She said the incident happened within the school grounds but outside the school’s front gate.

“I noticed a teacher running through the front gate calling ‘shut the gate, lock the gate – we need to call the police’ and then I saw the principal running out of the office,” she said.

“She was making sure the front gate was secured and there was talk amongst some of the parents that there was a domestic in the car park, and I did see a man on the ground being attended to by ambulance officers as I drove past.

“There was another deputy [principal] waiting along the pathway to stop any children from exiting through to the front of the school.

“I made my way up to the meeting point for my son and there was an announcement that came over the loud speaker letting students and parents know that for safety purposes there was to be no exiting through to the front gate at that point.”