An eight-year-old girl has been killed and four others seriously injured after a truck driver crashed into a rest-stop area on the southern outskirts of Sydney.

NSW Police said in a tweet that emergency services were responding after reports of the accident on the southern-bound side of the Hume Highway about 3pm.

An hour later, Channel Seven reported several people with serious injuries and at least 30 emergency services vehicles at the scene.

Tweet from @7NewsSydney

The truck driver was taken to hospital for mandatory testing before being charged overnight with nine offences, including two back-up offences.