Stuck in bumper to bumper #traffic on #880 after part of fence on overpass fell on fwy @abc7newsBayArea #abc7now pic.twitter.com/KSkUKxinGX — Natasha Zouves ABC7 (@NatashaABC7) October 20, 2015

Witness tells @abc7newsBayArea "We were lucky no one was killed" after tons of debris fell on busy I-880 in Oakland. pic.twitter.com/3bD9jXc0Qu — Laura Anthony (@LauraAnthony7) October 20, 2015

Expect delays in both directions on 880 at 23rd, more details to come but use 580 as an alternate. #Oakland — CHP Oakland (@CHPoakland) October 20, 2015

UPDATE: Fencing from the 23rd O/C has fallen onto both directions of 880. All lanes are blocked, unknown ETO. Use alt routes. #Oakland — CHP Oakland (@CHPoakland) October 20, 2015

UPDATE SIGALERT * SB880 at 23Rd, Oakland, the SB lanes have been reopened, the #1 lane NB is now open, — CHP Golden Gate (@CHP_GoldenGate) October 20, 2015

Approx 100 yrds of fencing fell onto 880 tonight at 23rd Ave causing at least 8 veh to crash in #Oakland. Freeway in clearing stages now. — CHP Oakland (@CHPoakland) October 20, 2015

All lanes now clear in both directions - 880 at 23rd in #Oakland. — CHP Oakland (@CHPoakland) October 20, 2015

OAKLAND, Calif. (KGO) -- Caltrans inspectors were out Tuesday looking at a freeway overpass that dumped tons of debris onto passing motorists.The incident happened last night along Interstate 880 in Oakland, at the 23rd Avenue overpass.One driver told ABC7 News he saw the whole thing happen right in front of him."I saw the guard rail and the fencing just peel loose essentially... One section came loose, pulled the other sections like a zipper," said Ian Steplowski.Steplowski says he first thought it was an earthquake or an accident on the overpass above as he and nine other cars founds themselves right in the middle of a sea of falling debris. Heavy metal fencing and rails came down on Interstate 880."I thought maybe it was an earthquake. I couldn't really explain it. I was just terrified for a long second there that that overpass was going to come down on me," Steplowski said. "We were lucky, we were very lucky yesterday that no one was killed."Several drivers had minor injuries, but no one was seriously hurt.Cellphone video shows firefighters and workers using a blow torch to cut up the debris last night.Several inspectors were out on the same overpass, trying to figure out exactly what happened and trying to making sure nothing else is about to fall."It definitely could've been worse and we're taking this very seriously and we want to find out what caused this," said Caltrans spokesperson Bob Haus.Caltrans is in the process of dismantling the 68-year-old overpass with a plan to replace it over the next two years.