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(CNN) -- Police in Buffalo, New York said Saturday evening that they have arrested and charged a suspect in connection with a shooting spree that left four dead outside a downtown restaurant earlier in the day.

The Buffalo Police Department said 25-year old Keith Johnson is in custody and has been charged with four counts of second degree murder.

Authorities would not comment on whether Johnson knew his alleged victims.

Eight people hit by bullets in the early morning rampage, police say. One of the four survivors is in critical condition.

At a news conference Saturday, Police Commissioner Daniel Derenda said that the dead -- two men and two women -- included a Texas man who was celebrating his wedding anniversary.

About 100 people were at the City Grill when the shootings occurred, and patrons were asked to leave the restaurant's bar after some sort of argument, police said.

City Grill posted a message on its website on Saturday, saying that it is "cooperating fully with the authorities and the ongoing investigation." It added, "Our thoughts and prayers are with the victims and their families."

CNN's Rick Martin and Alona Rivord contributed to this report.