Tensions are high along the border between Colombia and Venezuela, as a major push to deliver humanitarian aid could descend into violence on Saturday.

On Friday, musicians held a Live Aid Venezuela concert in border town Cucuta, Colombia to pressure Venezuelan leader Nicolas Maduro to let humanitarian aid into Venezuela, ending the show with a rendition of John Lennon’s “Imagine.”

Concert organizer Richard Branson also took the concert stage, exhorting the crowd in a chant of “Freedom” while pumping fists. The Venezuelan government was not pleased, blocking viewers in the country from watching the concert online and on certain television outlets.