Oil prices tumbled 4 percent on Wednesday, dragged down by a plunge in gasoline futures that triggered a brief halt in trade on the New York Mercantile Exchange.

Gasoline traded down 25 cents at midday in New York, stopping trade on NYMEX crude, heating oil and gasoline futures for five minutes, after falling early as concerns that the flooding along the Mississippi River would shut regional refineries eased.

Prices came off further after U.S. inventory data from the Energy Information Administration showed an unexpected build in gasoline inventories, the first rise in 12 weeks.

It was the second big drop in oil prices in a week, after Brent crude prices plunged 8.5 percent on Thursday.

Oil traded down early Wednesday after data showed China's industrial output growth eased much more than expected in April, suggesting the world's second-biggest economy is cooling. Consumer inflation eased modestly to 5.3 percent in April from a 32-month high in March of 5.4 percent.

Oil and product futures resumed their fall after trading in New York resumed, with U.S. crude down $4.94 to $98.94 a barrel at 12:50 p.m. EDT (1750 GMT). In London, Brent crude dropped $4.72 to trade at $112.91 a barrel.

U.S. gasoline for June delivery was down 29.17 cents to $3.0880 a gallon.

The EIA report of a build in gasoline stocks last week was a surprise, and that shook the market, adding to earlier worries about signs of cooling in China's economy, said Phil Flynn, analyst at PFGBest Research in Chicago.

The concerns about the floods along the Mississippi River have eased and the EIA data, which also showed crude stocks rose, is bearish, Flynn added.

(Reporting by Gene Ramos, Robert Gibbons, Janet McGurty, Emma Farge, Selam Gebrekidan, Eilen Moustakis and Joshua Schneyer; Writing by Matthew Robinson;editing by Sofina Mirza-Reid)