SAN DIEGO (CBS 8) - Immediately following 9/11, everyone had a heightened sense of security. If something looked suspicious, authorities were called. But over a decade later, some fear we're becoming too lax.
It seemed to happen without warning, but now it turns out black bags with pressure cooker bombs were left in multiple locations, and no one reported the suspicious activity before if happened.
Retired Colonel David Epstein has a deep understanding of acts like this. He served in the U.S. Department of State anti-terrorism office.
"If you see something suspicious, don't be afraid to pick up your phone and call 911. The police can't do this job alone," he said.
But what is suspicious? Colonel Epstein says trust your gut.
"Anything that you feel isn't right. A backpack left alone, a shopping cart with stuff left in it, left alone. A carry-on piece of luggage left in an airport terminal with no one around it. That's suspicious," Epstein said.
Tuesday at Lindbergh Field, we noticed TSA agents walking the security line and arriving passengers said they spotted added security where they boarded.
"We saw three dogs with the TSA people that we have never seen before," a traveler said.
Some members of one group in town to celebrate a friend's 60th birthday admit they were a little nervous Monday about the thought of getting on a plane Tuesday, but felt fine this morning. As for being complacent, they say 9/11 changed them forever.
"I think I'm more aware of where I am and who I'm around and what's going on around me," a visitor said.
Which is exactly what Colonel Epstein wants to hear. Because what happened in Boston Monday is a tragic reminder that we can never let our guard down.
"We're never going to eliminate it completely. There's always going to be a Timothy McVeigh wannabe out there and we have got to keep on fighting," he said.
Colonel Epstein knows his advice could lead to thousands of false alarms being called in to authorities, but says it's worth it if there's one real alarm.