Police have since issued notification that the incident was an attempted murder, reports news agency TT.
The accommodation for unaccompanied refugee minors where the guard was posted is now considered to be under threat, according to radio station Sveriges Radio P4 Väst.
“It is too vague to say exactly what this is about,” Sten Melander, duty investigation leader with the police in Trolhättan, told the radio station.
A silver Audi approached the centre at around 2am Saturday morning, before one or two people got out of the car before getting back in. A window was then wound down and two shots fired at the guard before the car drove away, reports TT.
The guard did not sustain any injuries.
“We have cordoned off the area for technical investigation,” information officer Christer Fuxborg of Police Region West told TT.
Children residing at the centre have been moved to alternative accommodation following the incident.