Twenty protesters were arrested Saturday after a clash between Occupy Denver protesters and police turned violent, with police officers shooting pepper spray at the protesters.Police responded in force at Civic Center Park Saturday afternoon after a situation with Occupy Denver protesters got out of hand, emergency dispatchers said.Dispatchers said Denver police were at the park to ask that tents be taken down at about 3 p.m. Police said the crowd became "unruly" sometime during their interaction.Denver police spokesman Matt Murray said five people were arrested a short time later. Two of those people were accused of attacking an officer and were arrested on felony assault charges.A few hours later, there was another wave of arrests after police moved in to remove tents from the park. Witnesses said police surrounded the tents and arrested protesters who refused to leave the area. Murray said 15 people were arrested in the second sweep.Following the arrests, police removed tents from the park and dragged them into South Broadway. A 7NEWS crew said Denver Public Works trucks were hauling the tents away.South Broadway was closed between 14th and West Colfax avenues for several hours.