By Denis Chabrol
BBC News, Georgetown
Police in Guyana are investigating the killing of Agriculture Minister Satyadeow Sawh at his home on Saturday.
His death is the latest in a string of gun crimes to rock the former British colony.
The minister and several members of his family had just returned home and he was reportedly relaxing on the patio when the gunmen invaded their premises.
Armed with assault rifles, they killed Mr Sawh, his brother, his sister and a security guard.
Another brother was treated in hospital for gunshot wounds.
The minister's wife hid in a section of the house, which is in the Earl's Court district, about six miles (10 kilometres) east of the capital, Georgetown. His two sons were not at home at the time of the incident.
No arrests have been made so far.
Guyana's ruling party is claiming that the minister was deliberately assassinated in the run-up to general elections later this year.
The People's Progressive Party said the killing was designed to foment hatred and violence ahead of voting due in this South American country any time after August 30.
Police Commissioner Winston Felix said the incident appears to have been a robbery in which the gunmen stole a little over $100 (£56).
But he did not rule out other motives - including political assassination.
Heavily armed gangs have flourished in recent years in Guyana, and efforts by the police and army to crush them have so far failed.
Mr Felix said police would push ahead with plans to improve security for politicians in and out of government ahead of polling day.
"The extent to which security concerns are being raised is more than justified," the commissioner said.
"With this incident, we have to now focus heavily on the security of persons in the category of ministers and to the best of our ability ensure their safety."
Mr Sawh was shot dead three months after the gunning down of Ronald Waddell, a television talk show host as well as a militant black activist and fierce critic of the administration.
Guyana's government and the political opposition are preparing to start negotiations on what constitutional arrangements should be put in place for governing the country before parliament is dissolved on 4 May.
Guyana's elections have been postponed from the constitutionally due date of 4 August.