BOSTON — Massachusetts Gov. Deval Patrick has declared a state of emergency and banned travel on roads as of 4 p.m. as a blizzard that could bring nearly 3 feet of snow to the region began to intensify.

Patrick said as the storm gains strength it will bring “extremely dangerous conditions” with bands of snow dropping up to two to three inches per hour at the height of the blizzard, prompting whiteout conditions.

Patrick said the travel ban will apply statewide and bans all motor vehicle traffic until it is lifted. The ban doesn’t apply to public safety workers and utility workers.

The MBTA is canceling all services as of 3:30 p.m.