By Trang Do

PHILADELPHIA (CBS) — Law enforcement across the country are on high alert following a National Terrorism Advisory System (NTAS) bulletin issued by Acting Secretary of Homeland Security David Pekoske. The department announced it has information to suggest that extremists who object to the results of the presidential election are continuing to mobilize and could incite violence as seen during the break-in at the Capitol on Jan. 6.

In an interview Wednesday on “CBS This Morning,” former Homeland Security Secretary Michael Chertoff said the Capitol riots exposed the real and growing threat of domestic terrorism.

READ MORE: Philadelphia Students To Remain Virtual As Mediation Process Between School District, Teachers' Union On Phased Reopening Nearing End

“I think we need to treat it as seriously as we have been treating global jihadism in terms of a threat to homeland security,” he said.

The Department of Homeland Security is urging people to avoid large crowds and protests and to be hyper aware of their surroundings.

Eyewitness News spoke to tourists visiting the Liberty Bell Wednesday who said they are acutely aware that these are tense times.

“I didn’t want to come here last week because of the inauguration and I didn’t know if there might be some very active protests going on, violent protests, here in Philadelphia, so I’m glad it’s a week later,” said Vickie Harcum, who was visiting from New York City.

READ MORE: Delaware County Company Develops 'The Hurricane,' Device Using UVC Technology To Kill Coronavirus

“I’m just hoping now that maybe, things will maybe settle, but ultimately people have the right to petition whatever their beliefs are,” added Chelsea Paredes, also of New York City. “I just hope that, as a nation, we can find more unity through difference of opinion.”

The Department of Homeland Security is asking people to report any suspicious activity or threats of violence, including online, to local law-enforcement or the FBI.

MORE FROM CBSPHILLY.COM

Jersey Devil Coaster — World’s Tallest, Longest & Fastest Single-Rail Roller Coaster — Set To Open At Six Flags Great Adventure

UK COVID Variant Spreading In Philadelphia Region, Deadly For One Person In New Jersey

MORE NEWS: Fourth Bucks County Resident, Raechel Genco, Arrested For Alleged Role In Capitol Riot

Philadelphia School District Students To Begin Hybrid, In-Person Learning Feb. 22