"Mr. Cliff" — that's what residents of the 5400 block of Diamond Street affectionately called their neighbor, 84-year-old Clifton Hickman.

Whether he was walking to church with his wife, Ann, or tending to his handmade birdhouses in his small patch of a front yard, everyone on the block knew Mr. Cliff. Everyone always said hello.

That's why so many were gathered on the block Sunday, mourning that Hickman, his wife, and a son had died overnight in a fire in Hickman's rowhouse. Another son was hospitalized with injuries.

"They were like family," said Gary Ras, 38, a longtime friend. "I wish I could say I knew them longer."

Authorities did not know what sparked the blaze, but said it did not appear suspicious. A neighbor said she called 911 after seeing the flames around 4:45 a.m. Capt. William Dixon, a Fire Department spokesman, said about 40 firefighters battled the fire for 39 minutes before it was deemed under control.

Police said Hickman was pronounced dead at Penn Presbyterian Medical Center at 5:37 a.m. His wife, 70, and the son, identified by family as Tyreke Johnson, 30, were declared dead at the scene.

The fourth victim, a 19-year-old who neighbors said was also a son, was hospitalized at Lankenau Hospital in stable condition, police said.

Karen Tunstall, 52, who said she has lived next door to the Hickmans for decades, was  getting Kool-Aid and ice when she saw smoke coming from the back of their house. She said she ran to the front door to yell for Ann Hickman. Tunstall said that she heard her get up but that neither she nor her husband made it out of the house.

Tunstall said she and another man attempted to open the door to get inside and help, but a cloud of black smoke almost knocked them off their feet.

"That smoke came right at us," she said.

Tracey Spencer, 29, who lives across the street, said she was awakened by someone screaming that there was a fire. She saw a plume of smoke coming from the Hickmans' house and called 911.

"I was in shock," Spencer said. She described the Hickmans as universally respected, saying they helped run a community gathering space at the end of the block and were friendly to everyone. People left Clifton Hickman his parking space when it snowed because he got around by using a walker, she said.

"If you needed to know something ... ask Mr. Cliff," she said.

Steve Gilbert, a nephew of the Hickmans', said he was with  Johnson just hours before the fire. Johnson had lived in Iowa for about a year, Gilbert said, and was home visiting his family.

Gilbert said he and Johnson had made plans to go fishing Sunday. Johnson had offered to find a bait and tackle shop to make sure they had enough supplies.

Instead of fishing, Gilbert spent the morning trying to comprehend the sudden loss of Johnson and his parents.

"I still can't really wrap my mind around it," he said.