ABC News' Lindsey Ellerson and Jennifer Parker Report: Several loud booms were heard outside of the Xcel Energy Center in St. Paul, Minn. at approximately 9:30pm ET, where the Republican National Convention is currently underway.
Sgt. Andrew Kubista, a National guardsman, told ABC News that law enforcement used "flash bangs," bright lights and loud noises, to break up protesters.
"They tried to scale the wall," Kubista said of demonstrators causing commotion near the large steel barricades setup around the convention site. Kubista estimated that 300 to 4,000 demonstrators were involved.
Bangs could be heard in the streets of St. Paul as police deployed canisters of green smoke to quell the protesting crowd. Members of the law enforcement were fully armed, wearing bullet proof vests and masks as well as carrying batons.
The entry to the Xcel center has currently been shutdown. No one is being allowed in and the gates are secured all around.