UPDATE: The statewide travel ban will be lifted at 4 p.m. ET on Saturday.

Anticipating “extreme danger conditions” throughout the Commonwealth, Governor Deval Patrick declared a State of Emergency just after noon on Friday, and banned all vehicles from the roads starting at 4 p.m.

As winter storm Nemo begins to descend upon Massachusetts, Patrick said safe travel on the streets would be “nearly impossible,” and signed an executive order to  keep drivers off the roadways during the duration of the storm.

“The travel ban applies statewide and bans all motor vehicle traffic starting at four, until the ban is lifted,” according to state officials.

The ban allows only public safety workers and public works vehicles critical to government functions to be on the roads.

A penalty for up to one-year in prison and a hefty fine could be handed out if the ban is violated.

“The point is not to figure out how to come down hard on people; it’s to emphasize that non-essential travel on the roads cease,” said Patrick. “We have to have as many people off the roads as possible.”

The state will not be collecting any tolls on roads starting at 2 p.m. so workers can get home safely.

Patrick has never had to sign one of these orders in the past, he said, during a press conference with reporters on Friday afternoon.

Other modes of transportion were also being brought to a halt on Friday. The MBTA announced that all service would be suspended starting at 3:30 p.m.

The last time the T stopped operations was during Superstorm Sandy.

With expectations of up to three feet of snow from the blizzard, Patrick said people should prepare to be shut in at home for the next 24 to 48 hours.

Winds could reach up to 55 miles-per-hour, and snow drifts could reach up to five feet.

According to the National Weather Service, a blizzard warning is in effect until 1 p.m. on Saturday.

During heavy snow bands, Nemo will be piling two to three inches of white powder per hour on the state, making for “extreme danger conditions.”

More than 1000 National Guards have been deployed already, and that number will hit 5000 over the course of the weekend, Patrick said.

“There will be great temptation to play in the snow [following the storm] and so forth, and I totally understand, but please, please exercise caution and use common sense,” Patrick said.

Patrick said storm recovery will be slow and people should prepare for that. Some of the precautions he advised were to monitor the progress of Nemo, and keep up with weather reports.

“There are hazards underneath this winter wonderland,” he said.

Additional briefings will be held as the storm develops over the next few days.