Authorities arrested and indicted a Tennessee man this week who threatened to assault and murder Rep. Diane Black.

Clifton Ward allegedly threatened to kill Black, a Republican who is running for governor of Tennessee, after she introduced the Border Wall Trust Fund Act to help the federal government pay for President Donald Trump’s envisioned wall along the U.S.-Mexico border.

Ward left a voicemail at one of Black’s district offices, officials told WKRN in Nashville.

“They were serious enough threats that the grand jury did take action,” Black said in an interview with Fox News Wednesday.

“This is not the first time — and it probably won’t be the last time — that when people get angry they do and say things that are threatening,” Black said. “I can tell you that they were very serious and they were threatening enough where they concerned the police.”

Lawmakers on Capitol Hill and their staffs have indicated that they have received an increased number of threats in recent years.

In her Fox News interview, Black referenced the near-fatal shootings of Arizona Rep. Gabby Giffords in 2011 and Louisiana Rep. Steve Scalise last June at a Republican baseball team practice where a gunman opened fire on more than 20 GOP lawmakers at a field that only two U.S. Capitol Police officers were patrolling.

“You never know when it is going to be serious as it was for Gabby Giffords and Steve Scalise and it’s very scary for our families,” Black said, adding that she feels more secure now that the man who threatened her has been arrested.

The Capitol Police has “widened the net” of events off Capitol Hill where the agency has acted to ensure protection for lawmakers since the shooting at the baseball field in Alexandria, Virginia, last spring, Chief Matthew Verderosa told the House Administration Committee in June.

The USCP has coordinated security with local law enforcement for over 400 events outside of the Capitol complex, including for member town hall meetings and other district events. Lawmakers have expressed concern over safety at remote events and meetings after the shooting and as political tensions have ramped up rhetoric and actions by citizens.

The number of threat assessment cases opened and investigated by the Capitol Police has nearly doubled, Verderosa said.

— Katherine Tully-McManus contributed to this report.

Watch: 20 Years Ago, a Deadly Shooting in the Capitol Changed Life on the Hill Forever