Cops rushing to the highway on Friday night?

Hey all, we’re driving back from dinner and while we were on the Southwest Freeway a bunch of cops put their sirens on in front of us and just stopped to block off the rest of the highway. Keep in mind it’s not even 9:30 yet so we’re just confused. We exited and are taking backroads through Richmond and we keep seeing cop cars suddenly turn their lights on and rushing toward the highway. Anyone know what’s goin on?