Caption: A general view of the wooden houses called ‘Palafitos,’ on the shore of Lake Maracaibo, Zulia State, Venezuela.

Three people were killed and six injured in an explosion Tuesday on an oil barge on Lake Maracaibo, in northwest Venezuela, state-owned petro giant PDVSA said.

The explosion, whose cause is unknown, occurred at dawn, the company’s security division said in a statement.

The barge was operated by a PDVSA subcontractor working on well maintenance near the border with Colombia.

Six months ago, two people died and four others were declared missing after the sinking of another barge of the same company on Lake Maracaibo.

The PDVSA had attributed that incident to “poor weather conditions.”

Lake Maracaibo, the largest in South America, was once the cradle of the Venezuelan oil industry.

Its facilities today are run-down due to years of mismanagement, corruption, a lack of investment, and the oil embargo imposed by the United States.

Venezuela’s oil production, which exceeded three million barrels per day (bpd) 25 years ago, is about one million bpd today, having fallen to less than 300,000 at its worst.

The country holds the largest oil reserves in the world.

US President Donald Trump said Monday he would levy a 25 percent tariff on any country buying oil or gas from Venezuela, which he accused of being “very hostile” to the United States.

It and many other countries do not recognize last year’s victory claim by President Nicolas Maduro in elections he is accused of having stolen.

The United States earlier this month gave energy giant Chevron one month to stop its operations in Venezuela, delivering a heavy blow to cash-strapped Caracas.