A beloved father of six was fatally gunned down in front of his brother outside a Washington Heights paella joint today — for supposedly looking at a thug the wrong way, authorities and the victim’s kin said.

“I knew they were trouble,” said Andrew Alvarado, 31, the grief-stricken sibling of Humberto Alvarado, 39, who was shot in the chest by one of three punks who concealed his weapon in a t-shirt.

Andrew said the bloodshed unfolded after he and his brother went out for a drink with some other family members to El Rey De La Paella Restaurant on West 181st Street near St. Nicholas.

Andrew said that just before 2:30 a.m., three men approached his brother inside the restaurant, with one asking why he was looking at them.

His brother denied staring at the guy, Andrew said, but the man punched him anyway and ran outside. As Humberto ran after him, one of his attacker’s cohorts then shot him.

Cops said they were unsure of the motive, but the victim’s family said they believe that the men may have come into the restaurant to hassle or even hurt a young woman who worked there.

They said Humberto didn’t know her.

The woman quit her job after the shooting, said the bar owner’s brother.

“She told me today that she’s never coming back to work after what happened last night,” said owner’s brother, Volivar DeLeon.

Meanwhile, Humberto’s wife, Carmen Maria Alvarado, was inconsolable.

“I lost my love! I lost Humberto! Oh, my God!” she sobbed inside the family’s apartment.

Andrew called his brother “a model to his children.

“He was a very responsible brother, cousin, and friend. He had no enemies,” he said.

Additional reporting by Jessica Simeone and Rebecca Harshbarger