C172 PLT AND A LIGHT TWIN HAD AN NMAC IN ZOA CLASS E AIRSPACE.

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IN RADIO CONTACT WITH SQL TWR. THE SQL CTLR HAD INFORMED US WE WERE #2 FOR LNDG; INSTRUCTED US TO RPT THE CEMENT PLANT FOR R BASE ENTRY FOR RWY 30; AND TO FOLLOW A C172 THAT WAS OVER THE CEMENT PLANT. WE HAD ACKNOWLEDGED THE CTLR'S INSTRUCTIONS. WE HAD BEEN MONITORING THE ATC FREQ BEFORE CALLING THE SQL TWR AND HAD HEARD NO TFC ALERT ISSUED TO ANOTHER ACFT IN THE VICINITY OF THE COYOTE HILLS AREA. AT THAT MOMENT; A PISTON PWRED TWIN ACFT (LOOKED TO BE A CESSNA TWIN) APCHING; WE ESTIMATE; FROM A 4-5 O'CLOCK POS WITH RESPECT TO OUR ACFT; PASSED OVER THE TOP OF US; CLRING OUR R WING BY ABOUT 20 FT; PULLED DIRECTLY IN FRONT OF US WITH AN ESTIMATED 50 FT CLRNC BTWN THE TAIL OF THE TWIN AND THE NOSE OF OUR ACFT. THE TWIN WAS IN A SHALLOW R TURN ATTITUDE. HAD NOT THE TWIN BEEN IN THIS SHALLOW R TURN ATTITUDE; THE L WING OF THE TWIN WOULD HAVE CUT OFF THE R WING OF OUR ACFT. THE TWIN THEN PROCEEDED TO MAKE A SHALLOW L DSNDING TURN TO ABOUT A 10 O'CLOCK DEP BEARING WITH RESPECT TO OUR ACFT; WE GUESS HEADED FOR THE PALO ALTO ARPT (PAO); ABOUT 10 NM TO THE S OF COYOTE HILLS. THIS ALL HAPPENED WITHIN A FEW SECONDS. THERE WAS ABSOLUTELY NO TIME TO TAKE ANY EVASIVE ACTION ON OUR PART TO AVOID A POSSIBLE MID AIR COLLISION. THE SQL TWR CTLR IMMEDIATELY CALLED TO GIVE US A TFC ALERT WARNING; STATING THAT HE SAW 2 TARGETS (ACFT) ON THE SQL RADAR AT THE SAME LOCATION AND SAME ALT OVER COYOTE HILLS. WE INFORMED THE SQL CTLR THAT WE HAD JUST BEEN PASSED BY A TWIN WITH CLRNC OF ABOUT 20 FT. WE PROCEEDED TO LAND AT SQL WITHOUT FURTHER INCIDENT.