South Australian man douses service station worker in fuel

A man is accused of dousing himself and an Adelaide service station worker in petrol and threatening to ignite the fuel.

Police were called to the siege at Modbury North service station, in Adelaide's northeast, just after 5.30am on Tuesday and negotiated with the man for an hour before arresting him.

Montague Road was shut down and police and firefighters were forced to storm the Coles Express outlet when communications broke down.

They managed to apprehend the offender after dousing him with a fire hose.

"The decision was made for the safety of the attendant that police had to enter. Water was doused on the offender and the attendant and police moved forward and took control of the offender," Supt Guy Buckley told 9NEWS.

Police locked down the service station for most of the day while crime scene investigators scoured the scene. 

The attendant escaped serious injury, but was taken to Modbury Hospital to be checked over.

The 44-year-old has been detained under the Mental Health Act and is being assessed in the Royal Adelaide Hospital.