San Mateo, CA – On May 9, 2025, at 9:30 p.m., the San Mateo Police Department responded to the Shell Gas Station located at 1400 West Hillsdale Blvd on the report of a “loud bang” heard by the gas station attendant. Officers arrived and located one spent 9mm shell casing at the scene. Through the investigation, SMPD Officers confirmed a shooting at an occupied vehicle occurred, suspect information was obtained for three involved adult males, and multiple arrest warrants were granted. No victims were injured as a result of the shooting.
SMPD learned that two of the suspects, Carlos Alegria and Elder Lariosmayen, were already in custody for an unrelated crime out of San Francisco. The third suspect, Junior Mayen Mujiana, was still outstanding. SMPD obtained arrest warrants for all three suspects, and Alegria and Larios had their warrants added to their current bookings in San Francisco.
On October 8, 2025, at 10:56 a.m., Mayen was arrested for his warrant in the area of Cypress Avenue and N. Amphlett Blvd. Search warrants were then executed at one of Mayen’s residences in San Mateo, and one at his other residence in Hayward. During the search, a Glock pistol, several rounds of ammunition, and gang indicia were located. Mayen was transported to the San Mateo County Jail where he was booked for his arrest warrant.
We ask our community members to stay alert. We need community support in reporting crimes and suspicious activities. If you see a suspicious person, vehicle, or activity, call SMPD. Trust your instincts. See Something, Say Something.
ARRESTED
Junior Mayen Mujiana, age 19, San Mateo resident
Carlos Alegria, age 22, Millbrae resident
Elder Lariosmayen, age 20, San Mateo resident
CHARGES:
Mayen-PC 32- Accessory after the fact, PC 186.22 (A)- Participate in a criminal street gang, PC 978.5- Felony bench warrant
Alegria-PC 245 (A) (2)-Assault with a deadly weapon, PC 246- Shoot at an inhabited vehicle, PC 29800(A)-(1)-Felon in possession of a firearm, PC 29900 (A) (1)-Possession of a firearm with previous conviction, PC 30305 (A) (1)-Prohibited person in possession of ammunition, PC 417 (A) (2) (A)-Exhibit a concealed firearm in public
Lariosmayen-PC 29800 (A) (1)-Felon in possession of a firearm, PC 29900 (A) (1)-Possession of a firearm with previous conviction, PC 30305 (A) (1)- Prohibited person in possession of ammunition, PC 417 (A) (2) (A)- Exhibited a concealed firearm in public
