In recent days, Congressional staffers have received an e-mail alerting them to a 20- to 30-foot “fireball— that will light up the sky above the Potomac River on Wednesday, thanks to the filming of a new CBS Paramount series about Washington FBI agents.

But the reality is a little less exciting. Officials from Washington, D.C.’s Motion Picture and TV Development Office said Tuesday that it will all be pyrotechnics — and thus not much of a fireball.

“You will see a flash for two seconds,— spokesman Joshua Friedman said. “But if you blink, you’ll miss it.—

Several e-mails have circulated throughout government offices, each with its own twist on the simulated explosion. One informs readers that a boat will be blown up. In fact, nothing will explode.

The one sent to Senate staffers recently is less sensational, reporting that the scene will include “a simulated explosion on a sculling boat, which will cause a 20’ to 30’ fireball about 2 seconds in duration, accompanied by a small plume of smoke and a low thud.—

That e-mail is tagged as a message sent “on behalf of the Capitol Police,— but spokeswoman Sgt. Kimberly Schneider said it did not originate with the department.

Friedman said the simulated explosion is really just a pyrotechnics display for a scene in the new show, “Washington Field.— The display will take place between 9:30 a.m. and noon Wednesday. The e-mail sent to staffers is right about the location, which is on the Potomac River just north of Key Bridge, near Water Street Northwest.

“The contained-pyrotechnic effect will involve a brief flash and plume of smoke that will last for only a few seconds,— Friedman said in an e-mail. “The scene will be filmed out on the open water, at a safe distance from any roadway, bridge, or other structure.—