Police arrested one suspect in a Kansas City. (Representational image)

Police arrested one suspect in a Kansas City, Kan., area bar mass shooting and were hunting for a second gunman early on Monday, in an attack that killed four people and wounded five, police said.

No motive was given for the early Sunday shooting, but one of the two men wanted was kicked out of the Tequilla KC Bar, a private club, late on Saturday, police said.

It took four people to throw the man out after he tossed a cup at a bartender who had refused to serve him, media including the Kansas City Star reported. Then the man started another fight just outside the bar before midnight.

The disgruntled man returned just before 1:30 a.m. Sunday with an accomplice, both armed with pistols, and the two started shooting, witnesses told the newspaper.

Police arrived to a scene of chaos after they were alerted to the incident, as the few dozen people who had been in the bar were running out. The suspects had fled and there was blood on the street, police spokesman Thomas Tomasic said.

Four people were killed and five wounded, police said, but the victims were not identified. Police said the wounded were in stable condition.

Resident Juan Ramirez told the Kansas City Star his 29-year-old nephew was among those killed.

Early on Monday, police posted online that a suspect, Javier Alatorre, 23, had been taken into custody, but they released no other details about the arrest other than that police were assisted by other agencies including the FBI.

Police also announced that a second suspect, Hugo Villanueva-Morales, 29, was wanted and they were each charged with four counts of first-degree murder.

Alatorre was being held on $1 million bond, police said.

Villanueva-Morales was considered "armed and dangerous", police said in a post Facebook.

Kansas City, Kansas, is about 4 miles (6.4 km) across the Missouri River from Kansas City, Missouri.