Foreign staff are holed up at the biggest diamond mine in Sierra Leone, which has been hit by a violent strike, the company's spokesman has said.
Hundreds of local workers at the mine in the eastern town of Koidu have blocked its entrance since Saturday.
The army has been deployed to Koidu where two people were killed in clashes on Tuesday, the police said.
It is said to be the worst conflict to hit Sierra Leone's lucrative diamond industry in recent years.
The government has been trying to improve the sector after "blood diamonds" sold on the global market fuelled the decade-long civil war that ended in 2002.
The BBC's Umaru Fofana reports from the capital, Freetown, that between 100 and 150 foreign staff are trapped at their residences in the mine compound, owned by a South African-based company, Octea Diamond Group.
Most of them are South Africans, but they also include Ghanaian, Zimbabwean, Namibian, UK and Indian nationals, he says.
Octea spokesman Ibrahim Sorie Kamara said the expatriates could not leave the compound because of alleged threats against them.
The company is concerned about their safety, and considering whether to evacuate them, he said.
Sierra Leone's Vice-President Samuel Sam-Sumana rushed to Koidu - the main mining town in eastern Sierra Leone - after violence broke out on Tuesday.
He continued with his mediation efforts on Wednesday, holding talks with workers and management.
His intervention came after police fired on protesters who allegedly threw stones at the convoy of Mineral Resources Minister Minkailu Mansaray, when he was in Koidu to deal with the crisis.
Residents accused police of shooting dead two people, our correspondent says.
Protesters then stormed the hospital in Koidu, taking the dead bodies and marching with them through the streets of the town, vowing to avenge the killings, he adds.
A police post in the town was also burnt, our reporter says.
Christmas bonus anger
Koidu police commander Chief Supt Saidu Jalloh said the army had been deployed to Koidu to help restore order, and a night-time curfew has been imposed.
Police opened fire after being "over-powered" by a huge number of protesters, Mr Jalloh said.
He confirmed there were two fatalities, but did not say how they were shot.
Our correspondent say the authorities have retrieved the two bodies taken from the hospital, which is now under the control of police.
Bike-riders, who provide a taxi service in Koidu, say one of their colleagues was killed in the shooting.
They have now joined the strike, refusing to transport passengers and demanding that the authorities hand over the body of their colleague, our reporter says.
Mr Jalloh said several people have been arrested in connection with the unrest.
Miners embarked on the strike to demand better pay and working conditions, accusing Octea of reneging on a promise to pay them a Christmas bonus, equivalent to three months' salary.
The company denied the allegation, saying the workers had been paid the bonus, our reporter says.
The workers are also demanding an improvement in what they describe as appalling working conditions and end to alleged racism, he adds.
Five years ago, the mine was also hit by conflict which left two people dead, our correspondent says.
Octea is the biggest investor in the diamond industry in Sierra Leone where the government is heavily dependent on the industry for its revenue, our reporter says.
The country's mining sector is often hit by strikes, but the police do not not usually respond with such force or call in the army, he says.