One of the deaths occurred after a tree fell on a country club in Huntingdon Valley.
It happened at the Philmont Country Club after straight-line winds ripped across the course shortly after noon.
"The tree came down onto the building then most of the building came down on the golf cart area where this gentleman was at," said Bob Scholly Jr., Lower Moreland Township Emergency Management coordinator.
"The storm blew in and everyone was rushing in, and before we knew it a tree fell," employee Kelli Patrick said.
Severe storms leave 3 dead in Montgomery County, including one at country club
There was a frantic rescue operation as crews tried to save the man but he did not survive.
ABC's Philadelphia affiliate WPVI learned the man killed was the Philmont Country Club's head pro, Justin Riegel, 34.
Riegel leaves behind a wife who was due to give birth later this month.
In Lower Merion Township, a woman was killed when a tree came crashing down while she was inside a vehicle.
Police have identified the woman as Jean Biegalski, 49, of Roxborough.
In a separate incident, in the Wynnewood section of the township, a tree toppled along the 1300-block of Medford Road, also killing a man inside a vehicle.
In Wallingford, Delaware County, a fire claimed a man's life on the 600-block of Morris Lane.
Neighbors said the storm hit, and they heard something that sounded like a transformer pop.
First responders said a power line went down at around the same time.
Numerous long-term care facilities lost power during the height of the storm, and 12 facilities were still using emergency generators by Wednesday evening. Officials said they are working to coordinate assistance, with special consideration given to "ensure continued isolation" of residents who have COVID-19.
In Lansdale, the storms damaged the roof of a 150-unit-apartment complex. The Lansdale Borough Emergency Management Agency is working with the Red Cross to coordinate housing for a large number of displaced residents.
Powerful storms damage roof of apartment complex in Lansdale, Pa.
The roof debris also landed on a Jeep.
"When I was outside the clouds were getting dark so we ran inside. We came to the door where we heard a loud crash and all the lights flickered on and off. As we looked outside there was debris flying down the street. We looked down and saw a car was trapped under the giant wreckage of the roof of the building behind me," witness Ryan Van Dame said.
No injuries were reported there.
The Montgomery County Emergency Communications Center received 1,537 calls for assistance in a one-hour period from noon to 1 p.m. For comparison, the center answers approximately 2,300 calls in an average day.
Storm damage from across the Delaware Valley
ComEd is sending more than 100 local employees and 100 contractors to support restoration efforts in Pennsylvania. More than 300,000 customers are without power, ComEd said.