It took just 30 seconds in Ohio and zero bullets in Texas for officers to stop two mass shooters in less than 24 hours this weekend, but the result was that 31 people were killed and dozens wounded.

Officers gunned down the Ohio shooter at the doorstep of a bar-turned-hiding place in the middle of Dayton’s nightclub district and arrested the El Paso shooter as hundreds fled a crowded shopping centre. Though the two attacks staggered a country accustomed to gun violence, the bigger shock may have been that the death toll wasn’t worse.

In the Texas border city of El Paso, a gunman opened fire Saturday morning in a shopping area packed with thousands of people during the busy back-to-school season. The attack has left 22 dead and more than two dozen wounded, many of them critically. Two of those killed died on Monday in hospital.

Hours later in Dayton, a gunman wearing body armour and carrying extra magazines opened fire in a popular nightlife area, killing nine and wounding more than two dozen people.

The attacks came less than a week after a 19-year-old gunman killed three people and injured 13 at the popular Gilroy Garlic Festival in California before dying of a self-inflicted gunshot wound.

The El Paso shooting was being investigated as a possible hate crime as authorities worked to confirm whether a reported racist, anti-immigrant screed posted online shortly beforehand was written by the man arrested. The border city is home to 680,000 people, many of them Latino.

Many life-threatening injuries in El Paso

El Paso authorities offered few details about the assault, but police Chief Greg Allen described the scene as “horrific,” and said many of the 26 people taken to hospital had life-threatening injuries.

In Dayton, the bloodshed was likely limited by the swift police response. Officers patrolling the area took just 30 seconds to stop the shooting, which unfolded around 1 a.m. on the streets of the downtown Oregon District, Mayor Nan Whaley said.

Video released by police shows Connor Betts, 24, being shot down by officers just steps away from entering a bar filled with hiding patrons.

Shooting suspect Connor Betts approaches a nightclub in Dayton, Ohio, early Sunday in a still image from surveillance video released by police in the city. (Dayton Police Department/Handout via Reuters)

Had police not responded so quickly, “hundreds of people in the Oregon District could be dead today,” Whaley said.

Betts’s 22-year-old sister, Megan Betts, was among those killed.

Authorities identified the El Paso suspect as Patrick Crusius, 21, from Allen, a Dallas suburb nearly a 10-hour drive from El Paso.

Mayor Dee Margo said he knew the shooter was not from his city.

Mourners attend a vigil on Sunday after a mass shooting in Dayton. (Bryan Woolston/Reuters)

“It’s not what we’re about,” the mayor said at a news conference with Gov. Greg Abbott and the police chief.

President Donald Trump tweeted Monday that Washington “must come together” in the wake of the shootings “to get strong background checks” for gun users, but provided no details on what sort of legislation he would support.

The Democrat-led House has passed a gun control bill that includes fixes to the U.S. firearm background check system, but it has languished in the Republican-controlled Senate.

Mourners place flowers and candles at the front of Ned Peppers bar gathering at the scene of a mass shooting before a prayer vigil Sunday night. (John Minchillo/The Associated Press)

Trump suggested Monday that a background check bill could be paired with his long-sought effort to toughen the immigration system. He didn’t say how.

Beto O’Rourke is a Democratic presidential candidate and former Texas congressman who is from El Paso. At a candidates forum Saturday in Las Vegas, he appeared shaken after receiving news of the shooting in his hometown.

He said he heard early reports that the gunman might have had a military-style weapon, saying we need to “keep that [expletive] on the battlefield. Do not bring it into our communities.”

The shootings were the 21st and 22nd mass killings of 2019 in the U.S., according to the AP/USA Today/Northeastern University mass murder database, which tracks homicides where four or more people killed — not including the offender.