The protest site, 580 kilometers (360 miles) south of Bangkok, was calm on Tuesday, after provincial authorities declared the area "off-limits" to protesters by enacting a special security order, said Suporn Atthawong, a deputy secretary-general to Prime Minister Yingluck Shinawatra.
"The government is evaluating the situation," Suporn told reporters. "Security agencies will determine if other laws, such as the Internal Security Act, are needed."
The internal security law authorizes officials to seal off roads, take action against security threats, impose curfews and ban the use of electronic devices in designated areas. Peaceful and unarmed rallies are allowed under the law.
Police Maj. Gen. Somchai Uamthanom said the violence was mainly caused by teenagers who had joined the protests.