COVINA (CBSLA.com) — Hazardous-materials crews responded Monday to reports of pepper-spray attack at a Covina Home Depot that sent four people to the hospital.

Los Angeles County Fire Department personnel were called to the store in the 900 block of West Badillo Street about 3 p.m. after a report of customers having respiratory problems resulting from an unknown chemical spill.

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Covina police say a verbal altercation between two male customers escalated, resulting in one of them discharging pepper spray into the face of one victim.

Police told CBS2/KCAL9’s Crystal Cruz that the men were former business acquaintances.

“The airborne pepper spray particles spread quickly to other parts of the store and affected numerous uninvolved persons,” Sgt. Rob Bobkiewicz said.

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Twelve patients were treated by fire personnel. Four of those patients were transported to a hospital with unknown injuries, according to police.

Witness Anthony Zambrano recalled seeing several patrons rushing out of the store and says he felt tingling in his throat as he left.

“Everybody just ran out, kind of like, you know, coughing, leaning over,” Zambrano said.

Fernando Aldana-Rivera, 38, of Covina was subsequently arrested on suspicion of unlawful possession/use of a tear gas weapon.

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A LAFD spokesperson said the area was determined safe shortly after 4:30 p.m.