The 401 had to be shut down in both directions in Cambridge on Tuesday night following a grass fire that officials say burned out of control at one point.

Witnesses describe seeing a ‘wall of flames’ along the 401 around 6 p.m.

The fire started in the area of industrial road and McGovern Road, just south of highway 401 and west of Hespeler Road.

It began to encroach onto the highway prompting Ontario Provincial Police to shut down the 401 between Shantz Hill Road and Hespeler Road.

About 25 firefighters from three stations responded alongside Waterloo Regional Police and OPP.

Cambridge fire officials said fire grew to be about 4 acres in size , but they did manage to bring it under control quickly.

Officials have not yet identified the source of the fire, but said it is a popular area for people who are homeless.

The highway was reopened just after 8:30 p.m.

There were no injuries or damages as the fire occurred on a grassy, vacant piece of land.