(CNN) -- Eyewitnesses to the collision of two news helicopters in Phoenix, Arizona, in which four people were killed, told investigators they noticed no problems with either aircraft before the collision, a National Transportation Safety Board spokesman said Saturday.
Police say suspect Christopher Jones will likely be charged with the deaths of the four killed in the crash.
Of the seven witnesses interviewed as of Saturday evening, none saw any pieces fall off the helicopters before the collision or noticed smoke or erratic movement by either aircraft, NTSB spokesman Steve Chealander told reporters. Witnesses also told the NTSB "go team" investigating the collision that they heard no change in the sound of the helicopter engines, Chealander said.
The helicopters were tracking a police chase through the streets of downtown Phoenix when they collided at midday Friday, crashing to the ground in flames and heavy smoke.
KTVK-TV photojournalist Jim Cox and pilot Scott Bowerbank were killed, as were KNXV-TV photographer Rick Krolak and pilot Craig Smith.
Witnesses said the KTVK helicopter appeared stationary when the KNXV helicopter struck it, Chealander said. "That's as good as we can tell you right now. That's as much as we know."
Charred debris from the helicopters remained scattered in a downtown park, which was closed to the public. Watch smoke and flames pour from debris »
The rotor blade from one helicopter hit the front windshield of a truck, but the driver was uninjured, and the blade imbedded itself in the asphalt, Chealander said. Another rotor blade was found on top of a parking garage about half a mile away, he said.
Chealander said eight NTSB investigators began arriving in Phoenix late Friday night. They will take the information they collect, including interviews with witnesses, back to Washington for analysis, he said.
The NTSB will issue a preliminary report on the crash within five business days, and the final report will be issued in about nine months, he said.
Chealander said a pond in the park where the helicopters crashed will be partially drained for any further evidence, and police divers would be sent in to recover the rest. Water in the pond has been tested and found not to be hazardous, he said.
"Our condolences go out to the families and friends of the victims," Chealander said. "It's heartbreaking to see these kinds of accidents."
Phoenix Police Chief Jack Harris said the chase began after police received a report of a stolen vehicle and began pursuing a suspect, who abandoned that vehicle and allegedly stole a truck. The truck was being chased at the time of the chopper collision.
The suspect, identified Saturday as Christopher Jones, later bailed out of the truck and barricaded himself in a house, where he was captured, police said.
Jones was arraigned Saturday on four counts of aggravated assault, two counts of theft of means of transportation and one count of resisting arrest. His bond was set at $1 million after a prosecutor told the judge Jones may flee.
"He put the entire community in danger. ... Everyone on the street was a possible victim," the prosecutor said.
Jones said in the hearing he blacked out in the house, and when he came to, police used tear gas and a Taser on him.
"I don't know how all this happened. I really don't," he told the judge.
Harris said Friday that Jones could face charges related to the four deaths. E-mail to a friend