The motive of the suspect, who police say is a "male of Hispanic or Middle Eastern descent, 6'0, thin build, with a heavy beard and wearing all black clothing and a black beanie", according to witness' descriptions, is now unknown.
Police safely evacuated diners from the restaurant and found the expended device, according to a Pasadena Police Department news release.
Garrett Gunkle, who was sitting with his wife at the bar, told KNBC-TV there was chaos as customers ran for the exits in the Los Angeles suburb.
A Cheesecake Factory in California hopes to return to normal business hours after a man threw a homemade bomb into the restaurant Thursday.
"People were jumping over one another, fighting to get over bar stools", he said. No getaway auto was seen.
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Authorities described it as "homemade pyrotechnic device" but did not disclose its contents. The Los Angeles County Sheriff's Department bomb squad responded and rendered the device and restaurant safe. The motive behind the freakish incident remains a mystery. The motive is not known, police said.
The man was wearing all black clothing and a black beanie, according to the Police Department.
No serious damage to the restaurant was visible inside the store on Friday morning.
Local authorities notified federal agencies out of an abundance of caution, but don't know if the incident was meant to be an act of terrorism, the Star-News said.
Tornek said he was driving by the Cheesecake Factory Thursday evening after leaving dinner and saw the police cordoning off the area.