Police in the south-east African state of Malawi say they have arrested 140 members of lynch mobs who attacked people suspected of being vampires.
At least eight people are believed to have been killed, including two men on Thursday in the second city, Blantyre.
One was set on fire and the other stoned, according to police.
Two others were arrested for threatening to suck people's blood but police say they have no medical reports of any actual bloodsucking.
Vigilante killings started on 16 September when three people suspected of being blood suckers were killed by a mob.
Traditional leaders in southern Malawi believe the vampire rumours started across the border in Mozambique where rumours of blood sucking have led to violence this week.
In Mozambique, protesters have targeted police because they believe they are protecting the supposed vampires, leading a northern town's administrator to flee the city.
The villagers in these areas believe human blood sucking is a ritual practised by some to become rich. They also believe they are failing to catch the blood suckers because they use magical powers.
If these communities believe in "mysterious magical explanations for things, then people will tend to attribute their difficulty on what they call blood suckers," Dr Chioza Bandawe, a clinical psychologist at the University of Malawi, said.
For some that represents "the life of the hope being sucked out of them," he said.
But this has been "expressed on innocent people or on people who are different".
James Kaledzera, Malawi's national police spokesperson, told the BBC that police patrols had been stepped up in areas affected.
He also said they would "arrest anybody who is deemed to have taken part in the killings".
A curfew has been imposed in parts of the south, and earlier this month, the UN instructed staff to move to safer areas.
President Peter Mutharika, who has been visiting the areas concerned, has vowed to investigate the killings.
Many aid agencies and non-governmental organisations work in Malawi, one of the world's poorest countries.
Educational standards are low, with belief in witchcraft widespread. Vigilante violence linked to vampire rumours also erupted there in 2002.