Facebook Inc. reported a 76.6 percent surge in quarterly profit on Wednesday, fueled by robust growth in its mobile ad business.

The company's shares were down slightly in choppy after-market trading.

Facebook said about 1.94 billion people were using its service monthly as of March 31, up 17 percent from a year earlier.

Analysts on average had expected monthly active users of 1.91 billion, according to financial data and analytics firm FactSet.

Mobile ad revenue accounted for about 85 percent of the company's total advertising revenue of $7.86 billion in the first quarter ended March 31, compared with about 82 percent a year earlier.

Analysts on average had expected total ad revenue of $7.68 billion, according to FactSet.

The social media giant is expected to generate $31.94 billion in mobile ad revenue globally in 2017, up 42.1 percent from a year earlier, according to research firm eMarketer.

That would give Facebook a 22.6 percent share of the worldwide mobile ad market, with arch-rival Google projected to be the leader with a 35.1 percent share, according to eMarketer.

Facebook has been updating its offerings and launching new features to keep users hooked.

Earlier in the day, the company said it would add 3,000 people over the next year to monitor reports of inappropriate material on its network and removing videos such as murders and suicides.

The move comes after videos of a fatal shooting in Cleveland and of a father in Thailand killing his daughter on Facebook Live were uploaded on the network, drawing widespread criticism.

Net income attributable to Facebook shareholders rose to $3.06 billion, or $1.04 per share, in the first quarter from $1.73 billion, or 60 cents per share, a year earlier.

Total revenue rose to $8.03 billion from $5.38 billion.

Facebook said it would no longer report non-GAAP expenses, income, tax rate, and earnings per share.

Facebook is also stepping up efforts to combat fake news, which emerged as a major issue in last year's U.S. presidential election.

Apart from the core Facebook network, which contributes a lion's share to the overall revenue, the company's photo-sharing app Instagram and messaging service Whatsapp also have a huge user base.

Facebook is the last of the top five U.S. tech companies to report quarterly earnings.