July 4 mass shooting foiled in Virginia: police
Police car lights (Shutterstock)

Police in Richmond, Virginia said Wednesday they had foiled a potentially disastrous mass shooting during the city's July 4 celebrations, the same day a man killed seven people at a separate parade in Highland Park, Illinois.

Richmond Police Chief Gerald Smith said police were tipped off by a member of the public who overheard a conversation on a plan to attack Dogwood Dell, the large city park where thousands were to gather for concerts and fireworks on the US Independence Day holiday.

The call led police on July 1 to a residence where they found one of two men potentially involved, with two assault rifles, a handgun, multiple ammunition clips, and 223 rounds of ammunition.

The person, identified as a non-US citizen, Julio Alvardo-Dubon, 52, was arrested on firearms charges.

The second suspect, Rolman Balacarcel, 38, was tracked and eventually arrested on July 5, on the same charges.

"Their intent was to conduct a mass shooting at our 4th of July celebrations," Smith told reporters.

He said authorities did not yet know the motive of the alleged planned attack.

Smith praised the unidentified person who tipped off police in Richmond, some 95 miles (153 kilometers) from the US capital Washington.

"There is no telling how many lives this hero citizen has saved with one phone call," Smith said.

Meanwhile the community of Highland Park continued to reel over the shooting there Monday in which 30 were wounded in addition to the seven killed by a gunman with a high-powered AR-15-style assault rifle.

Officials said that Robert Crimo, 21, had confessed to the crime and told law enforcement that he had mulled a second attack in a different city while he was on the run before his arrest.