Gunfire, involving live ammunition, will erupt Saturday near the White House and the Vice President’s residence in a test by the Secret Service.

The agency said it will run a “live fire” calibration of a system that makes it possible to determine exactly when and where shots are fired near the two high-security sites.

In the tests, which will run into early Sunday, shots will be fired into a “bullet trap,” an installation designed to prevent them from going astray. The trap has been tested and validated, according to the agency.

Shooting will be in three-shot increments, the Secret Service said.

From the description, it appears that the system will be similar to shot-spotter technology in use by the D.C. police.

It was not clear exactly where the shooting will occur. However, the agency said all streets bounding the Ellipse will be shut down during the test. These are E Street and Constitution Avenue to the north and south, and 15th and 17th Streets to the east and west. Part of Observatory Circle, near the Vice President’s residence will also close.

It was not known when on Saturday the shooting was to start.