A massive fire has broken out at a warehouse in California. In the early hours of Tuesday morning, a fire broke out at a warehouse in Ontario, California. The fire is currently under investigation, but authorities have arrested one person they believe is connected to the blaze. Take a look: The Ontario Fire Department is battling a 6 alarm warehouse fire. The building contains paper products. Units from many neighboring departments are on scene supporting the suppression efforts. pic.twitter.com/KLNykaMbgY — San Bernardino County Fire (@SBCOUNTYFIRE) April 7, 2026 The Desert Sun reported more on the blaze: A second-alarm, massive fire at an Ontario warehouse drew a large Riverside County mutual aid and fire-fighting presence Tuesday, the Riverside County Fire Department reported. One person was taken into custody in connection with possible involvement in the fire, Ontario Fire Department Deputy Fire Chief Mike Widdell told reporters at the scene. Fire crews responded to the Kimberly Clark Warehouse in the 9500 block at the Merrill Avenue at 1:45 a.m. Tuesday and found the approximately 1-million-square-foot warehouse ablaze. Ontario fire resources needed the assistance from Riverside County fire agencies to battle the immense blaze. The first-arriving unit reported heavy fire through the roof. Due to the heavy fire conditions, Ontario Fire Department requested a second-alarm augmentation from several outside agencies, including CAL FIRE and Riverside County Fire Dept., which brought in additional mutual aid resources, including 10 engine companies, one truck company, one squad, two battalion chiefs and one division chief, according to the county fire department. Here are some scenes of the fire: JUST IN: An absolutely TERRIFYING fire has erupted at a California warehouse in Ontario Firefighters are actively responding right now to the six-alarm fire "It is all hands on deck as they try to contain the blaze." pic.twitter.com/GtoUDUa3vd — Eric Daugherty (@EricLDaugh) April 7, 2026 Another angle: #BreakingNews – Footage from a Tik Tok user showing the active Commercial fire in #Ontario Ca. Holy Cow! https://t.co/OjNSEs76bK pic.twitter.com/6RtA7zOMk8 — CodeThreeNews (@CodeThreeNews) April 7, 2026 Drone footage of the blaze: Drone footage of the one-million square foot warehouse fire in Ontario, California. pic.twitter.com/C7dfyq1wdc — AZ Intel (@AZ_Intel_) April 7, 2026 ABC 30 reported the fire was caused by arson: An arson suspect was arrested after a massive fire erupted at a warehouse in Ontario, California, prompting a large response from first responders overnight. The fire was reported around 12:30 a.m. Tuesday near Hellman and Merrill avenues, according to the Ontario Fire Department. More than 100 firefighters were on scene battling the flames that cast an orange glow in the area. Massive fire tears through warehouse in Ontario Fire crews remained on scene several hours later as the fire continued to burn through the warehouse, estimated to be 1.2 million square feet. Officials say multiple people in the area called and reported hearing a loud boom when the fire first broke out. “This fire was very quickly identified as suspicious in nature,” said Deputy Chief Mike Wedell. “There was a subject of interest identified very early on in the incident. That subject has been arrested.” Wedell added that individual was taken to the police department to be interviewed by detectives.