At least one woman was killed and three others wounded when gunmen on motorbikes attacked Venezuelan voters taking part in a ballot challenging President Nicolás Maduro, AFP reported on Monday. Footage of the attack showed Venezuelans running and screaming, as some people sought refuge in a church.

Prosecutors said the incident is being investigated. The attack took place in Catia, a neighbourhood in the capital, Caracas.

The Opposition coalition blamed the attack on “paramilitary groups” linked to Maduro’s government. Nearly 100 people have died over the last four months in protests leading up to the election.

The call for polls was described as a “plebiscite” by the Opposition, but the government claimed it was “illegal.” Over seven million people have voted in the “plebiscite” so far, the Opposition claimed, according to AP.