A search is ongoing in eastern Texas for a gunman who opened fire at a Halloween party attended by "at least a couple hundred" revelers, killing one and injuring nine, according to police.

       The shooting started around 11:56 p.m. Saturday at Octavia's Activity Center in Texarkana, according to a statement Sunday morning from the Texarkana Police Department.

       "When they (police officers) got there, they encountered a large number of people running from the building and several inside suffering from gunshot wounds," the police statement reads.

       The gunman left the venue in a vehicle, setting off a massive search in eastern Texas.

       Texarkana Police Department via Facebook

       Police respond to a shooting at a Halloween party in Texarkana, Texas, Oct. 30, 2021.

       A 20-year-old man, whose name was not immediately released, was mortally wounded and later pronounced dead at a hospital, police said.

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       Nine other people wounded in the shooting were taken to Wadley Regional Medical Center and CHRISTUS St. Michael Hospital by ambulance and private vehicles, authorities said. None of them initially appeared to suffer life-threatening injuries, police said.

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       Officer Shawn Vaughn of the Texarkana Police Department said numerous 911 calls were made, prompting all patrol officers working at the time to respond, while another patrol shift was summoned to handle calls on the street, according to ABC affiliate station KTBS in Shreveport, Louisiana.

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       "When we got here, I understand there was a large crowd in the parking lot involved in several fights," Vaughn said. "So, we requested assistance from any and everybody that was available."