A major highway has been closed in both directions after a serious multi-car crash south of Brisbane.

Emergency services were called to the Mount Lindesay Hwy at Cedar Grove, near Logan, just after 8am on Sunday.

Four cars were reported to have crashed, with paramedics assessing nine people.

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One man in his 20s was rushed to the Princess Alexandra hospital with suspected pelvic injuries.

Two other people were taken to the Gold Coast University Hospital.

The highway remained closed as of 10.30am according to QLD Traffic, with motorists advised to avoid the area or expect lengthy delays.

Police remain on scene and are investigating the cause of the crash.