US police have arrested a suspect after six people were killed in a shooting attack on an Independence Day parade in Highland Park, Illinois.
Robert E Crimo III, 22, was detained after a brief chase, police said.
The gunman climbed on to a roof, shooting randomly at spectators using a high-powered rifle.
It is the latest mass shooting to hit the US - there has been one in every week of 2022. President Joe Biden said he was "shocked" by the violence.
Mr Crimo was detained after a manhunt. He was referred to as a "person of interest" in Monday's shooting, but after his arrest police said they believed he was responsible.
The gunman began firing at members of the public from the rooftop of a shop at around 10:15 local time (15:15 GMT), just a few minutes after the parade began.
What should have been a day of celebration quickly turned to panic, with pushchairs, purses and lawn chairs abandoned as crowds fled from the scene. Some witnesses said they thought the sound of gunfire was fireworks or a car backfiring.
One man, who was having breakfast at a nearby Starbucks when the shooting happened, told the BBC that 30 people came running into the coffee shop looking for cover. But they all had to be evacuated because they thought the gunman was trying to get in through the back door.
Five adults were killed at the scene and one died later in hospital. At least two dozen others were injured.
One of those who died has been named as Nicolas Toledo, a man in his late 70s, who was only there because he requires full-time care and his family did not want to miss the event.
"What was supposed to be a fun family day turned into a horrific nightmare for us all," his granddaughter Xochil Toledo wrote on GoFundMe.
"As a family we are broken, and numb. Our condolences go out to all the other families who lost a love one today."
Another victim of the shooting has been named as Jacki Sundheim, who was described by her local synagogue as a "beloved" member who taught and worshipped there.
"There are no words sufficient to express the depth of our grief for Jacki's death and sympathy for her family and loved ones," a statement by North Shore Congregation Israel synagogue said.
No charges have been filed against Mr Crimo and there is no indication of any motive.
Social media firms suspended accounts apparently belonging to Mr Crimo, who posted rap videos under an alias as well as videos depicting shootings, gun violence and other violent themes.
He also posted pictures of himself draped in a Donald Trump flag and a video of him greeting Mr Trump's motorcade at an airport.
The attack in Highland Park comes just a month after deadly shootings in Uvalde, Texas and Buffalo, New York.
The the Gun Violence Archive, a group tracking gun violence incidents across the US, says there have been almost 250 mass shootings in 2022 alone - defining these as incidents where at least four people are shot.
Illinois Governor Jay Robert Pritzker warned that mass shootings were becoming an "American tradition".
"There are going to be people who are going to say that today is not the day, that now is not the time to talk about guns. I'm telling you there is no better day and no better time then right here and right now," the Democratic governor said.
President Biden vowed to keep fighting "the epidemic of gun violence" in the country.
"I'm not going to give up," he said, speaking outside the White House in Washington.
Last week, the president signed the first significant federal bill on gun safety in nearly 30 years.
It imposes tougher checks on young buyers and encourages states to remove guns from people considered a threat - but critics say the measures don't go far enough.
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