Police said the bear is scared and bouncing from place to place, and the noise and activity are making it harder to trap.
A Wilmington resident with the Twitter handle @Jimmy_Tries recorded video of when the bear made its way into his backyard Thursday morning.
In the video, he shouted, "The bear's in our backyard! Holy [expletive.] Oh, mama. There it is!"
The bear then made its way on the porch, before jumping over the fence.
"No way! No way! Bear watch!" he shouted.
ABC7 Chicago's sister station WPVI in Philadelphia followed the bear's journey with their helicopter Thursday, as those on social media dubbed it #Delabear.
WATCH: Bear on the move in Wilmington, Delaware
"One of the cooks in the back saw it," said Joe McCoy who owns Catherine Rooney's restaurant on Delaware Avenue. "It was kind of walking upright down Pennsylvania Avenue headed towards the Brandywine."
The bear was also spotted on train tracks near the local ACME. It crossed the tracks with only seconds to spare before a train came speeding down the tracks.
Police asked those that live in the area of 14th and Clayton streets to bring their pets inside, stay inside and refrain from making noise.
A spokesperson for Delaware Natural Resources Police says the bear looks to be younger and possibly around 200 pounds. Wildlife officials don't know whether it's a male or female. It was shot with a tranquilizer gun Thursday morning, but the dart fell out, and the bear kept running and hopping fences in and out of backyards.
At around 11 a.m., it disappeared into the Alapocas woods.
Delaware's Department of Natural Resources and Environmental Control has closed the wooded areas and trails at Alapocas Run State Park in Wilmington until further notice due to the sighting of a black bear.
Residents like Susan Tate, who lives in San Diego but is from Wilmington, drove around the city trying to get a glimpse of the bear that now has a nickname.
"I'm keeping my eye out for 'Dela-Bear,'" said Tate. "I want to meet him."
The Delaware Natural Resources Police discourage anyone from approaching the bear.
Wildlife officials in Pennsylvania and Delaware have been working together to monitor the black bear that has been seen about a dozen times over the past six days.
Delaware authorities said the bear was spotted in several places early Wednesday morning north of Wilmington.
A photo released by New Castle County police showed the bear walking through Darley Green apartments off of Philadelphia Pike in Claymont, Delaware.
It was also spotted around I-95 near the I-495 split, and briefly on the grounds of Salesianum School before running back into the woods.
The bear has been caught on several surveillance cameras over the past week as it traveled through Delaware County, starting in Radnor and making its way down to Clifton Heights and Aston Monday night.
Anyone who sees the bear is asked to call the Delaware Natural Resources Police at 1-800-523-3336.