A tragic incident unfolded outside a popular comic convention in Melbourne, leaving one person dead and another critically injured after a car reportedly veered into a crowd.

Authorities report that a grey Toyota mounted the curb on Langs Road, near the Melbourne Showgrounds, shortly after 5 p.m., striking two pedestrians.

One of the pedestrians, whose identity has not yet been confirmed, was pronounced dead at the scene.

The other victim was rushed to the hospital with injuries described as life-threatening.

Victoria Police have detained a man in connection with the incident and plan to question him further.

At the time, the Supanova Comic Con was taking place at the venue, attracting thousands of attendees.

A major crime scene has been declared, with SES also on scene.

Witnesses told 9News they saw a car driving “at speed” towards a group of people, and it has been described as a “chaotic situation” at the scene.