Police have cordoned off a Caltex in Auckland's Glen Eden and arrested three people following an aggravated burglary overnight

Officers descended on the West Auckland service station on West Coast Rd just before 12.30am.

Police say the alleged robbers smashed their way into the service station before the sole employee activated a fog cannon and moved to a secure place.

The till was stolen and the alleged offenders fled in a getaway car waiting outside.