At least one gunman fired several shots outside the state Capitol on Thursday afternoon, prompting a brief lockdown and shutting down traffic as Denver police secured the scene. Police said no injuries were reported.

Police closed Colfax Avenue from Lincoln to Grant streets, and there were several officers and squad cars at the scene. Police spokesman Jay Casillas said authorities didn’t know yet if there were one or multiple shooters. No one was in custody.

“Should there be any threat to the public, we will make proper notification to residents,” police said in a tweet.

Lobbyist Mike Beasley had just left the Capitol and was at the corner of East 16th Avenue and Sherman Street when the shooting started. A car, driven by a woman, was parked in the middle of the intersection at Sherman and Colfax and a man was shooting toward at least three young adults who were running southwest over the hill on the Capitol’s lawn, he said.

Large swath of Colfax closed pic.twitter.com/J89wDbz8Bo — Jesse Aaron Paul ☀ (@JesseAPaul) January 4, 2018

“Initially I thought it was a car backfiring, and I’m trying to have a phone conversation at the same time,” Beasley said. “But after the third ‘backfire,’ I looked over my shoulder and saw a gun out of a car with smoke coming out of it.”

The car turned left and sped away, heading east down Colfax, he said.

“It seemed like an hour,” he said. “The state trooper was outside within seconds and Denver police within seconds after that. I’m guessing it didn’t last more than 30 seconds.”

Dustin Cabellos was near the Capitol when he said he saw a gun being fired from a vehicle toward the building, which houses the legislature and the governor’s office. Cabellos dived behind a barrier.

“There was a lot of traffic at the time,” Cabellos said.

Shell casings in the streets but do we really want a real-life Wild West shootout to open the stock show? pic.twitter.com/pHrMQTRdkL — Noelle Phillips (@Noelle_Phillips) January 4, 2018

The Colorado State Patrol, which is in charge of security at the Capitol, received reports of the shooting at 1:36 p.m. and temporarily placed the Capitol on lockdown. A state patrolman told bystanders in the Capitol there were 15-20 shots. Several shell casings could be seen on the north side of Colfax on westbound lanes.

Joshua Crews, 36, said he was waiting at Colfax and Broadway for the East Colfax bus. He heard a dozen or so shots before getting on the bus, he said. Then as he rode the bus past the state Capitol, police stopped it just west of Grant Street.

“The cops wanted to see everybody’s hands,” Crews said.

Gov. John Hickenlooper was in his office at the Capitol at the time, but he said: “To my knowledge … it had nothing to do with me.” The governor speculated that the shooting stemmed from a drug deal, but police have not commented about a possible motive.

#COgov Hickenlooper on shooting outside Capitol: “To my knowledge .. it had nothing to do with me.” Suggested it was part of a drug deal gone bad #COpolitics #coleg pic.twitter.com/g01Bur0FMQ — John Frank ☀️ (@ByJohnFrank) January 4, 2018

Police warned drivers to expect delays.