The suspected E Paso gunman has been charged with capital murder, with the District Attorney Jaime Esparza saying he will seek the death penalty.
“The state charge is capital murder. We are seeking the death penalty,” he said at a press conference on Sunday.
The gunman stormed a Walmart jammed with back-to-school shoppers on Saturday, killing 20 people and injuring 26 others.
The incident was the 250th mass shooting in the U.S. in 2019.
Hours later in Dayton, Ohio, another gunman opened fire on people in a popular downtown area.
The Sunday shooting left nine people dead and 27 injured.
The suspect in Dayton was shot and killed by officers.
The latest incidents come at a time when fresh calls for tighter gun control laws have emerged.
New Jersey Senator Cory Booker has expressed his support for the calls to avail stricter gun laws, saying the U.S. seems to be “accepting the idea that these [shootings] are going to be a regular occurrence”.
The two incidents have prompted orders from President Donald Trump to have U.S. flags flown at half mast.
“God bless the people of El Paso Texas. God bless the people of Dayton, Ohio,” President Trump said.