A bag featuring a swastika and containing a severed pig’s head was left at a school’s front gate on Wednesday, targeting Muslim schoolchildren in Brisbane’s south.

Early on Wednesday, Islamic College of Brisbane staff removed the bag before students arrived, but witnesses said they were shaken by the incident.

“They're worried because, while it's a minor thing, there are really young kids who go to that school, because it goes from Prep to year 12, acting school chairman Ali Kadri said.

“It's about the safety of the kids. If somebody's going to do this, given the climate, anything else could happen as well,” he noted. “So it's really scary.

He added that some young males in a Subaru WRX were caught on school cameras and the footage had been passed on to police. The camera footage is quite clear, he said.

Yassmin Abdel-Magied, a former student of the school, took to Twitter to voice her disgust at the incident on the college in which she spent her primary education.

“How is a parent supposed to explain to a kid why people hate them?” she said. “I'm just so sorry. I'm so so sorry we have to live in a world where kids can't go to school in Australia without being shamed and threatened.”