(CNN) -- A spate of fireworks debacles and tragic parade accidents wrecked Independence Day celebrations across the country.
The mishaps Thursday left 20 people hospitalized in Southern California, two people dead in parades nationwide, two people seriously injured in Chicago and $1.5 million in damage in Seattle.
Two people killed in parades
In Oklahoma, an 8-year-old boy on a parade float was killed when his father accidentally ran over him, Edmond police said.
The boy was on a martial arts float that was driven by his father, police spokeswoman Jennifer Monroe said. It's unclear whether the boy jumped or fell from the float before he was run over by the trailer's tires.
Another tragic parade accident took place in Bangor, Maine, when a man driving a tractor in the Independence Day parade died after a vintage fire truck struck him from behind, authorities said.
Bangor police Sgt. Paul Edwards said the parade had been rerouted because of a four-hour standoff with a gunman who fired several rounds at police from an apartment window.
The parade participants "would not have been on that street normally," Edwards said.
Fireworks shows gone awry
A display in Simi Valley, California, turned disastrous when fireworks exploded low to the ground and injured at least 26 people.
Twenty-three of the 26 people who were treated at Simi Valley Hospital were released by Friday morning, said hospital CEO Kim Milstein. One person was transferred to a burn center and two people were admitted to the hospital and were in fair condition.
Among those who were treated and released was a 17-month-old child. Injuries involved burns and shrapnel wounds, she said.
Witness Annisa Wynn told CNN affiliate KTLA that fireworks suddenly began shooting sideways into the crowd instead of up into the air.
"The fireworks were so close, you could see them on the ground," Wynn said. "It never happens this way. People were screaming."
The show, carried out by a pyrotechnics company, was part of an annual series of fireworks displays that began in the city in 1970, police Chief Mitch McCann said. Investigators were collecting evidence Friday, and the main investigation probably will begin Monday, Ventura County Deputy Fire Chief Mike LaPlant said.
Another show in Windsor, Colorado, sparked flames that rose 10 feet high over parched land, witness Kami Gilmour said.
"The first embers dropped and looked like it might have started a small tree on fire," Gilmour said. "Then we realized there were six or seven fires all along the field, and then a gust of wind came and blew the fire all over the place. ... Our car was about 50 yards from it and covered in soot."
There was no immediate word of injuries from the Colorado fire.
Fireworks sever woman's foot in Chicago
An apparent near-ground fireworks explosion severed a woman's foot and also seriously injured her sister-in-law in Chicago's West Lawn Park on Thursday night, CNN affiliate WGN reported.
The explosion severed the left foot of Kristina Perez, 32, and left fourth-degree burns on the left leg of Lorena Perez, 34, WGN said.
"One of the firecrackers, instead of going up, went to the ground and hit Kristina," her father, Eleuterio Carmona, told WGN.
The women said they were watching a fireworks display at the park when the explosion happened. Both were in serious condition at a hospital Friday, WGN said.
The display was not an official, regulated show, the station reported.
Illegal fireworks destroy 14 boats
Seattle authorities said illegal fireworks sparked a massive fire that caused $1.5 million in damage.
A firework landed on a boat cover at a boat storage facility on the north end of Lake Union, Seattle Fire Department spokesman Kyle Moore said. He said the dry storage facility stacks boats four stories high.
Within seven minutes, the fire had destroyed 14 boats.
Seattle also had three roof fires started by fireworks, according to Moore.
CNN's Jake Carpenter, Dave Alsup, Dottie Evans and Mayra Cuevas contributed to this report.