Three city residents have died while shoveling snow or operating snowblowers in the past 10 days as a succession of snowstorms left giant drifts and buried sidewalks, driveways and roofs under more than 2 feet of snow, Jessica Grondin, a spokeswoman for the city of Portland, said Thursday.

Grondin said a postal service worker found an 83-year-old man leaning over the top of his snow blower on Jersey Avenue. The other victims, a 55-year-old man and a 78-year-old man, died while shoveling. Grondin said the 55-year-old collapsed as he was taking a break from shoveling his driveway on Grant Street. Someone found the 78-year-old man behind a porch door after he had been shoveling his Woodlawn Avenue driveway.

“It is not unusual to have one death during a winter, but to have three deaths this close together is unusual,” said Portland Fire Chief Jerry LaMoria.

LaMoria advised people who have to shovel their driveways or sidewalks to either let someone know they are out shoveling or shovel with another person.

“No one knew anything was wrong (with the 83-year-old man) until it was too late,” said LaMoria, who advised people to stay hydrated while shoveling.

He also advised anyone who uses a roof rake to remove snow to avoid touching power lines. Many roof rakes are aluminum and could conduct electricity.

Dr. John O’Meara, a cardiologist at Maine Medical Center, said the hospital treats several cases of cardiac arrest whenever there is a snowstorm.

“We see it pretty much every snowstorm. People are putting stress on their bodies and their hearts in a way that they typically don’t,” O’Meara said. “This type of activity puts much greater stress on your heart than something like walking does.”

O’Meara said anyone with a history of coronary artery disease should avoid shoveling. If it can’t be avoided, shovelers should use common sense and not overexert themselves, listen to their body’s signals and take frequent breaks. Shortness of breath, fatigue and chest discomfort are warning signs, he said.

Chris Kimble, a meteorologist with the National Weather Service in Gray, said Portland has broken a seven-day snowfall record set in 1934. Kimble said 38.5 inches of snow fell at the Portland International Jetport from Jan. 27 to Feb. 2, topping the old record of 38.1 inches.

Thursday morning’s snowstorm dropped another 2.5 inches on the city.

And more snow is coming.

Kimble said that Saturday through Monday, Portland could get up to six inches of snow. Kimble said the accumulation will be gradual, with light snow on Saturday and Sunday and heavier snowfall arriving Monday.

Though snow isn’t expected Friday, it will be cold with the high temperature in Portland expected to reach only 15 degrees.

Parking bans have been instituted in several cities, including a citywide ban in Portland from 10 p.m. Thursday to 6 a.m. Friday, and a ban in Brunswick from midnight to 7 a.m. Friday.

Thursday morning’s snow likely contributed to a tractor-trailer jackknifing on the Maine Turnpike in Wells that closed the highway for about 90 minutes.

The rig blocked all three northbound lanes and traffic was diverted at the York exit, said Stephen McCausland, spokesman for the Maine Department of Public Safety.

According to Maine State Police, the driver told troopers he hit his brakes to avoid colliding with a vehicle ahead of him.

The driver, Carlos Tells, 29, of Columbus, Georgia, wasn’t injured and damage to his truck was described as minor.

A wrecker removed the truck.