Two illegal immigrants were arrested in a mass shooting plot at the Richmond, Virginia, July Fourth celebration.

"A hero citizen picked up the phone and overheard a conversation there was a mass shooting being planned here in the city of Richmond, Virginia," Richmond Chief of Police Gerald Smith said Wednesday.

Richmond suspects

52-year-old Julio Alvarado-Dubon and 38-year-old Rolman Balacarcel. (Richmond Police Department)

Two illegal immigrants, 52-year-old Julio Alvarado-Dubon and 38-year-old Rolman Balacarcel, were arrested and charged with being a non-U.S. citizens in possession of a gun after police uncovered a plot that the duo planned a mass shooting at Richmond's July 4 celebration Monday.

At a press conference Wednesday, Smith said that police investigated Alvarado-Dubon based on a tip to police by someone he would only refer to as a "hero citizen." Police investigated the claims and found Alvarado-Dubon was in possession of two rifles, one handgun, and 223 rounds of ammunition. He was arrested on July 1, while Balacarcel was placed under surveillance and eventually arrested on the same charges on Tuesday.

HIGHLAND PARK JULY 4 SHOOTING SUSPECT HAD TWO PRIOR INCIDENTS OF SUICIDAL, VIOLENT THREATS, POLICE SAY

Richmond July 4 suspects

Richmond Police Chief Gerald Smith listens to a question.

"There’s no telling how many lives this citizen hero saves from one phone call," Smith said. "One phone call saved numerous lives on the Fourth of July."

Both suspects are currently being held at Richmond City Jail with no bond, while no motive for the plotted attack has been released.

"We know what their intent was but we don't have a motive," Smith said.

Guns, ammunition

Two rifles, a handgun, a cache of magazines, and several hundred rounds of ammunition. ammunition (Richmond Police)

Smith addressed reports that one of the suspects has been deported several times and continued to re-enter the country illegally, saying that it was "frustrating" that a person could continue to break the law and have an opportunity to still plan out a mass murder.

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The news comes the same week a gunman in Highland Park, Illinois, identified as Robert E. Crimo III, opened fire on a crowd during the city's July 4th celebration.

July 4 suspects Richmond

Police say that they thwarted a planned July 4 mass shooting in Richmond, Virginia, after receiving a tip that led to arrests and the seizure of multiple guns.

Like Alvarado-Dubon and Balacarcel, Crimo had shown signs that he may be plotting an attack, but red flag laws in the state were not able to thwart the massacre.

"In September 2019, ISP received a Clear and Present Danger report on the subject from the Highland Park Police Department. The report was related to threats the subject made against his family," Illinois State Police said in a statement.

Fox News' Bradford Betz contributed to this report.