A 4.2-magnitude earthquake struck off the Malibu, California, coast early Wednesday followed by multiple aftershocks.

According to the U.S. Geological Survey, the first earthquake happened at 2 a.m. local time about 10 miles south of Malibu Beach and 15 miles southwest of Santa Monica. The depth was reported at about 9.2 miles, according to the USGS. The quake was “too small” to trigger alerts to local cellphones, the USGS said on Twitter.

Just seconds after the first jolt, a second earthquake was reported – a preliminary 3.5-magnitude earthquake, also 10 miles south of Malibu Beach. The depth for the second earthquake was reported at about 8 miles, according to USGS.

The Los Angeles Fire Department said in an alert that it had entered into “Earthquake Mode,” adding that all 106 stations across the city would begin surveying for damage.

Aftershocks of 2.8-magnitude and 2.6-magnitude struck the same area, according to USGS.

“The LAFD is now in earthquake mode. All 106 neighborhood fire stations will conduct a strategic survey of their districts, examining all major areas of concern (transportation infrastructures, large places of assemblages, apartment buildings, power-lines, etc). This survey will be conducted from the ground, air and sea. Once this process is complete and reports are consolidated, assuming there is no significant damage, Earthquake mode will be complete. This process typically takes less than one hour,” Nicholas Prange with the Los Angeles Fire Department said in a statement, per Fox 11, around 2:30 a.m. Wednesday morning.