"We have to get it stopped, this has been going on for years and we have to get it stopped," Trump told reporters on the tarmac at Morristown, NJ as he prepared to board Air Force 1 with the first lady to return to the nation's capital.
The president said he would make a statement on the shootings Monday. Trump said he has spoken to FBI Director Christopher Wray, Attorney General William Barr and members of Congress.
"This is also a mental illness problem," Trump said of the mass shootings. "These are people that are very, very seriously mentally ill."
The president's comments were similar to remarks made by Texas Gov. Greg Abbott in the aftermath of the mass shooting that killed 20 people and wounded 26 more at a Walmart in El Paso.
"Mental health is a large contributor to any type of violence or shooting violence," Abbott said on Saturday.
Democrats are calling for stricter gun laws in the wake of the shootings. Presidential candidates Beto O'Rourke and Sen. Cory Booker said Trump bears responsibility for the shooting in El Paso due to his anti-immigrant rhetoric.
Police in El Paso detained a 21-year-old white male suspect named Patrick Crusius, who they believe posted a racist screed on the internet before the shooting. The diatribe said the shooting "is a response to the Hispanic invasion of Texas." Trump has repeatedly referred to migrants crossing the U.S. southern border as an invasion.
"This president is encouraging greater racism and not just the racist rhetoric, but the violence that so often follows," O'Rourke, who comes from El Paso, said in an interview with CNN's "State of The Union" on Sunday.
Acting White House Chief of Staff Mick Mulvaney, in an interview on "Meet The Press," rejected the idea that Trump's rhetoric has in any way contributed to white nationalist violence.
"I blame the people who pulled the trigger," Mulvaney said.