“It sometimes feels like we’ve gotten too much of what we wished for with South by Southwest,” said Stephen Harrigan, 65, a novelist and a writer-at-large for Texas Monthly who has lived in Austin since 1966 and who walked the crowded downtown streets with his wife a few hours before the crash. “South by Southwest has upped the ante of what Austin is, and Austin is trying to play this game with itself, to try to compete with itself, to see if it can succeed in pulling this off.”

The city’s police chief, Art Acevedo, told reporters that officers watching for drunken drivers had tried to stop a motorist about 12:30 a.m. outside a service station near the nightclubs and other sites hosting events for South by Southwest, also known as SXSW. But the driver suddenly sped off, heading the wrong way down Ninth Street, a one-way street in downtown Austin, before turning onto Red River Street, where he rammed through a police barricade and struck a moped, a bicyclist and a taxi, in addition to hitting pedestrians, Chief Acevedo said.

The suspect, Rashad Charjuan Owens, 21, was caught by the police after he tried to flee on foot. A female passenger on the moped was killed, as was the bicyclist, who was visiting from the Netherlands, the police said. Mr. Owens was arrested but not formally charged, and he was expected to face two counts of capital murder and multiple counts of aggravated assault with a motor vehicle, the authorities said. The police were investigating whether he had been intoxicated.

In the aftermath of the crash, as three of the wounded remained in critical condition, residents, business owners, city officials and festival organizers and attendees engaged in a kind of citywide soul-searching. There were no calls to cancel the festival, as many defended the organizers, saying it was an accident that could have happened during any festival in any city.