WASHINGTON — The Department of Homeland Security will start construction of prototypes for a border wall this summer in the San Diego area, agency officials said on Tuesday, the first step in fulfilling a campaign promise made by President Trump.

Homeland security officials said the prototypes would be added to the existing border walls in San Diego and would allow the agency to evaluate which barriers are most effective in giving Border Patrol agents time to respond to illegal drugs and human smuggling. Officials said they planned to build four to eight prototypes but did not say when construction would begin.

“We own that land, have access to it and it’s a good place to start testing in a real-world environment,” Ronald D. Vitiello, acting deputy commissioner at Customs and Border Protection, said at a news briefing.

John F. Kelly, the secretary of homeland security, has said that there are no plans to build a wall along all 1,900 miles of the border with Mexico, which Mr. Vitiello has also said.