Authorities are looking for a man who used a sledgehammer to attack the owner of a Little Havana convenience store. After knocking him unconscious, he took off with two cartons of Marlboro Reds.

Yue Kui Cen, 44, remained in critical condition at Jackson Memorial Hospital on Monday evening. Detectives from Miami’s homicide unit are investigating alongside robbery detectives because of the severity of Cen’s injuries.

About 12:15 p.m. Sunday, the man entered Alex’s Mini Market, at 501 NW 12th Ave., just blocks from the new Marlins stadium.

He grabbed two gallons of milk and approached the register, where Cen stood. Nobody else was inside at the time.

A store security camera captured what happened next.

As Cen rang up the purchase, the man pulled out a spray bottle from his pocket. He sprayed an unknown chemical in Cen’s face. As Cen rubbed his eyes, the man walked around the front counter an removed a sledgehammer from his pocket.

Then he hit Cen six times over the head.

Afterward, the man stole two $12 cartons of cigarettes before walking out and riding away on a mountain bike.

On Monday, the victim’s wife, Phuong Thuy Ly Cen, said the man isn’t a regular customer. The Chinese couple moved to Miami about 22 years ago and opened the Little Havana store about six years ago. They have an 11-year-old daughter and 7-year-old son.

Phuong Thuy Ly Cen said she couldn’t sleep Sunday night.

“This guy is crazy. He’s crazy. And he’s out there,” she said during a news conference at police headquarters. Then she directed a message to her husband’s assailant: “The police will look for you and the people will help me look for you.”

Police have yet to identify the man, although they believe he lives or works in the neighborhood. Homicide detective Fernando Bosch said the man seemed to have planed the attack before walking into the store.

“This individual knew what he wanted. He knew what he was doing,” Bosch said. “He had the chance to try to open the register; he didn’t do that.”

Bosch echoed Phuong’s plea for help from the community.

“When you see a person like this victim, a family man, it makes you want to split yourself into pieces to find this guy,” he said. “This individual has to get off the streets.”

Anyone with information is asked to call the Robbery Unit at 305-603-6370 or Miami-Dade Crime Stoppers at 305-471-TIPS (8477).