Irvine-based online game maker Blizzard Entertainment Inc. helped drive first-quarter results for Santa Monica’s Activision Blizzard Inc.

Blizzard, which makes online video games played by millions, saw first-quarter sales of $357 million, up 17% from a year earlier.

The unit posted an operating profit of $170 million, up nearly 8% from a year earlier.

Blizzard’s flagship “World of Warcraft” game drove the results.

In December, Blizzard released the latest version of the fantasy game, “World of Warcraft: Cataclysm.”

About 12 million people play “World of Warcraft,” facing off in epic online battles as two fictional races fight for control of a fantasy world.

Blizzard’s gain helped drive Activision Blizzard, which still gets the majority of its revenue from games for video consoles.

Activision Blizzard’s sales for the quarter were up 7.6% from a year earlier to $1.4 billion.

Downloads for the company’s “Call of Duty” console game also helped drive sales.

The company’s online subscriptions—made up largely of “World of Warcraft,” other Blizzard games and “Call of Duty” downloads—rose 27% to $395 million in the quarter.

Blizzard is the largest software company based in Orange County with yearly sales of about $1.4 billion.

The company is part of France’s Vivendi SA, which bought Activision in 2008 and combined it with Blizzard in a deal valued at about $10 billion.