Officers responded to numerous reports of gunfire heard near a home in the 1200 block of Madera Avenue at about 4:30 a.m., Menlo Park police Sgt. Ed Soares said.
Police determined that two neighboring homes appeared to have been hit by bullets, Soares said.
Officers searched one of the homes to check on residents' welfare and found four people inside, along with two high-capacity assault rifles, a 9mm semi-automatic handgun and 10 ounces of marijuana, Soares said.
They also found numerous shell casings in the home, which indicated that shots had been fired from inside the residence, police said.
No one was injured.
Police arrested Menlo Park residents Kenntha Hahn, 28, Deangelo Williams, 22, Jerry Coneal, 18, and Chariece Chew, 19.
The four were booked into San Mateo County Jail for numerous weapons offenses, marijuana sales, possession of a controlled substance and conspiracy, and are suspected of being part of a criminal street gang, police said.
Anyone who has information about the case is asked to call Menlo Park police Sgt. Ed Soares at (650) 330-6360 or Detective Sgt. Jamie Romero at (650) 330-6361.
