A strange pattern of lights in the sky over San Diego late Monday prompted questions from social media users.

Twitter user @caatmamasaam posted the videos that garnered hundreds of reactions showing rows of two and three lights appearing beside each other in the San Diego night sky.

"Somebody explain the lights in the sky in San Diego," the user wrote.

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Another user, @gabegunlock, who posted a similar video to Twitter said the lights appeared for "about an hour."

San Diego mystery lights

Strange lights in the San Diego sky prompted questions from social media users on Monday. ( Sam Zarate / Local News X / TMX)

"Multiple floating lights over the ocean. Very still, very bright. Orange, reddish light. Patterns of 2, 3, 4, 5, and 6," the user wrote. 

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While many users suggested the lights may be unidentified flying objects (UFOs) or extremely bright lights that reach the Southern California city from Tijuana, Mexico, the San Diego Police Department told FOX 5 San Diego that lifeguards believe the lights may have been flares in a military exercise. 

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Imperial Beach in San Diego will be hosting a 4th of July drone show in place of fireworks this year, but City Manager Sandra Cowan told Fox News Digital that "the lights from yesterday are not related with the upcoming event."

"The company we’re hiring did not perform any testing," she added.