An overnight duplex blaze has claimed the life of a man in the Cobourg area.

Fire crews were called to the scene of the blaze at 4:30 a.m. at University and Ontario Streets.

Four of the five people living in the duplex escaped, but one man in his thirties was trapped by the flames.

Chris Sauve made a desperate attempt to rescue the man trapped inside.

"As soon as I opened the door, the fire alarm started going on and smoke started billowing out," Sauve told CTV News on Wednesday.

"I could hear him yelling but I couldn't get in there. It was just so smoky. I had a cloth over my face and I was pushed back. I took about three steps inside and that was about as far as I could go."

The flames were so intense, fire crews couldn't get inside the burning residence.

"The first arriving crew made every attempt they could to try to get in and there was just no way with the heat. The smoke was so intense that they couldn't make their way upstairs," Cobourg Fire Chief Allan Mann told CTV News.

The man was pronounced dead at the scene.

Flames also consumed a two-storey home in Port Hope on county road 10 on Tuesday night.

A young mother and her 20-month-old daughter escaped without injury.

The Fire Marshal's Office is investigating the fatal fire. The cause remains undetermined.

With a report from CTV's Jim Junkin