Shops, bars and restaurants were reopening in Dayton's trendy Oregon District on Monday as the proud Ohio city limped toward normalcy one day after a horrific shooting rampage that left nine people dead, dozens injured and the motive unknown.

Law enforcement officials were reluctant to speculate what set off 24-year-old gunman Connor Betts. Dayton Police Chief Richard Biehl said Monday that authorities were "not close at all" to determining a motive.

Betts' sister, Megan, 22, was among those killed in the shooting. Biehl said the siblings rode to the city's popular Oregon District with another person who was injured in the attack. But Biehl could not say whether those relationships prompted the shooting, which began just after 1 a.m. as the bars were closing down.

Betts' first victim was shot in an alley. He then emerged onto a street, where Megan, a student at Wright State University in Dayton, was among the first to die, police said.

"It seems to defy believability that he would (intentionally) shoot his own sister, but it's also hard to believe that he did not recognize his own sister," Biehl said, adding that there was no indication the others new of Betts' plan. "So we just don't know."

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There was no early indication that Betts was in any way inspired by the El Paso massacre Saturday that left 22 dead. Patrick Crusius, the man charged in that rampage, had posted a detailed, racist manifesto online decrying an "invasion" of immigrants.

Betts, like Crusius, was white. Six of the nine people Betts killed were black.

"We are not seeing any indication of race being a motive," Biehl said. "But we are still going through all the evidence."

Betts was killed within 30 seconds of firing the first shot from his assault-style rifle. Biehl said Betts arrived at the scene with as many as 250 rounds of ammunition. He fired at least 41 rounds; the officers fired more than 60, Biehl said.

President Donald Trump ordered flags at military installations, federal facilities and the White House be flown at half-staff until sunset on Thursday. In a brief address to the nation Monday, Trump condemned racism and bigotry and said he would press for mental health law reforms to "better identify mentally disturbed individuals" before they can pull a trigger.

He made no mention of stricter gun control measures, but did urge social media companies to do more to identify online warning signs of violence. And he directed the Justice Department to expedite executions for mass killers.

Critics have questioned whether Trump's anti-immigrant rhetoric spurred the shooter to action in El Paso, given the detailed manifesto officials linked to Crusius that mirrored much of the language Trump has used decrying a possible "invasion" from immigrants.

Trump raised the immigration issue in a tweet before his address Monday.

"We cannot let those killed in El Paso, Texas, and Dayton, Ohio, die in vain," he wrote on Twitter on Monday morning. "Republicans and Democrats must come together and get strong background checks, perhaps marrying this legislation with desperately needed immigration reform. We must have something good, if not GREAT, come out of these two tragic events!"

Dayton Mayor Nan Whaley said many small businesses in the Oregon District that are normally closed on Mondays were opening this Monday to show they would not be intimidated by the Betts' brutality.

Betts was a student at Sinclair Community College in Dayton, though he was not enrolled at the school for the summer. According to his LinkedIn page, Betts' work history included stints at Chipotle Mexican Grill and a gas station in Centerville, Ohio.

Moira Cofer Betts and her husband, Stephen, got the news within hours of the shooting. Police and FBI agents swept into their home in the Dayton suburb of Bellbrook, searching for evidence that could help explain what happened.

Bellbrook Police Chief Doug Doherty said they were "floored" when they were told what their son had done – to the community and to their own family.

"We don't know the why, we don't know the whats," said Bellbrook Police Chief Doug Doherty. "But we do know that there's a mom and dad down there that are really hurting."

Contributing: Monroe Trombly, Cincinnati Enquirer