The police have sealed off a district near the capital, Hanoi, after residents seized police hostages during a violent clash over a land dispute.
Reports say that as many as 30 officials, many of them police, are being held captive in Dong Tam commune, My Duc, about thirty kilometres south-west of the capital.
Journalists have been prevented from entering the area, as the police build up their forces in the surrounding districts.
Police units were driven out of the commune on Sunday by crowds of residents who pelted them with rocks and other missiles.
The hostages appear to have been seized during the melee.
The clashes erupted after police moved in on Saturday and arrested a number of people who have been involved in a long simmering land dispute with the authorities.
The arrests led to the violent response by residents who are demanding the release of their comrades in exchange for their hostages.
Leaders of the protest have taken over the public loud speaker system in the village and have been broadcasting messages to explain their case.
They say that none of the officials being held have been harmed and they are being well treated.
The confrontation is reported to have been triggered by an attempted seizure of land by the telecom operator, Viettel.
Disputes over land are common in Vietnam. Farmers in disputes across the country have complained that land they have worked for years is seized for development projects with often derisory compensation payments.
Violent clashes on the scale of the current dispute, however, are rare.
The police have dealt harshly in the past with land rights activists. Leading figures in prominent cases have been sentenced to lengthy jail terms as local officials attempt to assert their authority.