The ultranationalist Right Sector group was in a tense standoff with Ukrainian authorities after a deadly shooting in the western city of Mukacheve that killed at least two people, according to reports Sunday. Security forces called for the group's surrender in order to avoid a"bloodbath," Radio Liberty reported.

A Right Sector spokesman claimed on Sunday that armored vehicles had blockaded the entrance to Right Sector's base in the Lviv region, and said that law enforcement officials were blocking access to other Right Sector buildings across western Ukraine. The news came after about 20 Right Sector fighters -- who were reportedly cracking down on the illegal smuggling of cigarettes and other contraband -- became involved in a gun battle after arriving at a sports complex controlled by Ukrainian lawmaker Mikhail Lano.

Authorities said Sunday that Right Sector members had camped in the woods near Mukacheve and were refusing to surrender their weapons. Previous reports suggested that police had surrounded some gunmen in the woods and were trying to negotiate their surrender.

Lano said that a Right Sector commander had contacted him for help in arranging treatments in a sanatorium for men who had fought in the ongoing conflict in eastern Ukraine, and said that an unknown man was shot inside during the talks, according to the Guardian.

A video posted online by lawmaker Mustafa Nayyem on Sunday appears to show Right Sector gunmen firing rifles and a truck-mounted machine gun, apparently at police who had arrived on the scene. However, Right Sector spokesman Alexei Byk said that the video had been intentionally distorted and that the sounds of them being fired upon were removed, the KyivPost reported.

Multiple clashes were reported around the Mukacheve area, and helicopters and heavy vehicles were seen moving toward the area.

Medical authorities in the area said that 11 people, including police officers and civilians, had been injured in the shootout. Right Sector said two of its members had been killed and four others injured. Hundreds of Right Sector protesters had also gathered in Kiev and other major Ukrainian cities to support the organization.

Right Sector's activities have been deeply controversial and subject to international condemnation. The group has been allowed to continue operating by the government, and its paramilitary wing has been involved in conflicts against separatist groups in the country's east. They also played a role in the 2014 protests that overthrew the government of former president Viktor Yanukovych. However, rights groups including Amnesty International have accused Right Sector fighters of being involved in extrajudicial detention and torture.