WASHINGTON - The U.S. Secret Service is investigating an online survey that asked whether people thought President Barack Obama should be assassinated, officials said Monday.

The poll, posted Saturday on Facebook, was taken off the popular social networking site quickly after company officials were alerted to its existence. But, like any threat against the president, Secret Service agents are taking no chances.

"We are aware of it and we will take the appropriate investigative steps," said Darrin Blackford, a Secret Service spokesman. "We take of these things seriously."

The poll asked respondents "Should Obama be killed?" The choices: No, Maybe, Yes, and Yes if he cuts my health care.

The question was not created by Facebook, but by an independent person using an add-on application that has been suspended from the site.

"The third-party application that enabled an individual user to create the offensive poll was brought to our attention this morning," said Barry Schnitt, Facebook's spokesman for policy.

Because the application was disabled, the responses to the nonscientific polls are not available.

"We're working with the U.S. Secret Service, but they'll need to provide any details of their investigation," Schnitt said.