NEW YORK -- The price of oil sank nearly 3 per cent as a slowdown in China's growth added to doubts about the strength of the world economy and global demand for crude. It fell further after the close of trading when a bombing at the finish line of the Boston Marathon killed two people.

The Chinese government on Monday said growth in the world's second-largest economy slowed to 7.7 per cent in the first quarter from 7.9 per cent in the final quarter of last year. Growth was expected to accelerate slightly after several quarters of decline.

That slowdown, combined with weak economic reports from the U.S. and Europe's malaise, suggests that demand for crude and refined fuels won't be strong enough to absorb the ample supplies on the world market.

West Texas Intermediate, the benchmark crude in the U.S., dropped $2.58, or 2.8 per cent, to finish at $88.71 a barrel on the New York Mercantile Exchange. Earlier in the session, it hit $87.86. Crude hasn't been that low since December, and it's dropped more than 8 per cent in the past two weeks.

Brent crude, which is used to price oil used by many U.S. refiners to make gasoline, fell $2.41 to end at $100.63 a barrel on the ICE Futures exchange in London. It briefly fell below $100 for the first time in nine months.

Just as regular trading closed, two bombs exploded at the Boston Marathon finish line. Two were killed and dozens injured. Three hours after the bombing, President Barack Obama said the government was still not sure who was responsible.

By 6 p.m. EDT, WTI had dropped 1.4 per cent to $87.48 while Brent was down 1.3 per cent to $99.31 in electronic trading.

U.S. gasoline prices were lower Monday. The average price for a gallon of gasoline fell 3 cents over the weekend to $3.53. That's 26 cents lower than the high for the year, set on Feb. 27. And gas is now 38 cents cheaper than a year ago.

In other futures trading on the Nymex:

-- Wholesale gasoline fell 4 cents to finish at $2.76 a gallon.

-- Heating oil dropped 4 cents to end at $2.83 a gallon.

-- Natural gas fell 9 cents to finish at $4.14 per 1,000 cubic feet.

Pablo Gorondi in Budapest contributed to this report.