A woman, believed to be in her 30s, died after the blaze in Harvest Road, Smethwick, broke out in the early hours of Saturday morning.
The woman, thought to have been upstairs when the fire took hold, was rescued by firefighters after being found unconscious in a bedroom but was later pronounced dead.
Two other people, understood to be the woman's mother and father, survived after managing to get out of the semi-detached building with the help of fire crews.
Ashmetullah Faizy raised the alarm when he saw the flames taking hold, having got back from work just after 4am.
Mr Faizy, 38, said the fire became fierce enough to break the windows of the house as he was on the phone to 999.
He knocked on the door of the burning house along with the next-door neighbour before helping the couple who escaped and giving the man his trousers.
Mr Faizy told the Express & Star: "It was about 4.10am, I just came out of work and I just parked the car and went upstairs.
"As soon as I did that, I see from the window, I notice a light. I quickly came down the stairs, opened the door and saw the fire.
"I was the first person to ring 999. So I rang 999 straight away and I went and knocked their doors because they were upstairs.
"Then the husband has come out and the fire was getting really bad.
"I was on the phone with 999 and basically the fire started breaking the windows, everything.
"I knocked the other doors of the neighbour because they have got kids, telling them to get out of the house.
"Basically, everybody was asleep. I was on the phone with the fire people and then they arrived.
"They arrived really quick to be fair, and I rang straight away as soon as I saw some lights in the lounge. Then the fire was getting really bad.
"Everybody was asleep, I was just arriving from work when the fire basically began.
"The daughter was upstairs, I think. I just gave them some chairs, they came here, his wife was sitting here, and the husband has come out.
"I gave him some clothes because he came out without trousers, so I just gave him my trousers. The daughter (was) stuck upstairs. Then the fire people take her out and took her."
The house was left gutted following the blaze, with every window on the outside of the house blackened and charred.
The cause of the blaze has not yet been confirmed, with fire investigators examining the house on Saturday afternoon.
Police officers were also at the scene.
A spokesman for West Midlands Fire Service said: "At 4.35am this morning we responded to reports of a house fire in Harvest Road, Smethwick.
"Four fire engines and 19 firefighters responded, from Oldbury, West Bromwich, Woodgate Valley and Smethwick fire stations.
"This was a severe fire which affected all of the semi-detached house.
"Very sadly, a woman believed to be in her 30s, who was found unconscious in a bedroom and rescued by firefighters, was shortly afterwards confirmed by the ambulance service to have died.
"A man and a woman, believed to be in their fifties, were led to safety and given first aid by our crews. They were treated and taken to hospital by the ambulance service.
"Our thoughts are with them and everyone affected by this incident.
"The fire was confirmed to be out by 6.20am and, an hour later, our resources at the scene were scaled down to one fire engine.
"Investigators from West Midlands Fire Service will be working with police colleagues to establish how the fire started."