One of the parents outside Rhws Primary School this morning told ITV News: "You just feel lucky it wasn't you."
Martin Rauch said the Rhoose collision occurred on the same route his family walks to the school.
"We go down that side of the road," he said.
"We cross at that crossing, with that lollipop lady. It could easily have been us."
He added that the community was in 'a state of shock'.
Five adults and four children have been taken to hospital with injuries.
First Minister of Wales Carwyn Jones said: "I am very concerned to hear about this morning's incident in Rhoose and I am being kept fully informed of developments.
"Clearly, our thoughts are with those involved."
Police say nine people have been taken to hospital following this morning's collision in Rhoose - four with 'significant injuries'.
Officers are asking anyone who witnessed the collision, or who gave assistance, to contact the South Wales Police Serious Collision Investigation Unit using the 101 number.
Police added the school, which is open, is currently contacting pupils' parents.
The Vale of Glamorgan Council is offering support to both school and pupils.
A Wales Air Ambulance spokesperson says it treated three patients at the scene of the Rhoose collision but no one was flown to hospital.
A statement said: "We can confirm that Wales Air Ambulance (WAA) landed on scene at an RTC near a primary school in Rhoose.
"WAA crew from the Swansea base were tasked at 9:00am and on scene at 9:20am. The crew flew through adverse weather conditions to make it to the scene.
"The aircrew treated three patients on scene but did not convey any patients to hospital. Adverse weather continued to close in and the patients were assessed as suitable to travel by road.
"WAA left the scene at 10:48."
The Welsh Ambulance Service has confirmed it attended a traffic collision on Fontgary Road in Rhoose at 8:55am.
The spokesperson added there are no details yet regarding the severity of the injuries.