Rowe told reporters at a press conference Friday that the Secret Service did not have a drone up at the rally, even after local law enforcement requested to fly one.
The acting Secret Service chief said he was looking into the incident and also made a change to now "leverage" the use of drones.
"We are putting those assets out," he said. "We should have had better line of sight on some of those high ground concerns, we thought we might have had it covered with the human eye but clearly we are going to change our approach now."
The Secret Service has failed to swiftly implement new technology, such as drones, for decades, The New York Times reported this week. Rowe admitted the Secret Service also failed to communicate over the radio with local law enforcement on July 13.
Rowe, who has repeatedly called the Pennsylvania rally a "failure," also admitted the Secret Service should have had better coverage of the warehouse roof where Crooks fired from.
"That building was very close to that outer perimeter and we should have had more of a presence," he said.
The Secret Service has been grilled since the July 13 shooting, leading to the resignation last week of former director Kimberly Cheatle.
Local police were aware of Crooks as a suspect for more than an hour; the Secret Service failed to include the warehouse he fired from in a zone of security that local police did not have the resources to cover; and the federal agency reportedly denied requests in the past from Trump's campaign for more security.
A new AP-NORC poll found that only 3 in 10 Americans think the Secret Service can keep presidential candidates safe. Most Americans also blame political divisions for the assassination attempt, the poll found.
The case is still under investigation from the FBI, which has yet to determine a motive for Crooks, the 20-year-old killed by Secret Service counterfire shortly after he fired an AR-15 style rifle into the crowd, grazing Trump's ear and coming inches from killing him.
Rowe has also come under scrutiny for the July 13 failure, with Sen. Josh Hawley (R-Mo.) accusing him of being behind cuts to the agency's threat assessment division, citing a whistleblower.
The senator argued the cuts could have impacted the agency's ability to detain Crooks ahead of the shooting.
"The whistleblower claims that if personnel from [the division] had been present at the rally, the gunman would have been handcuffed in the parking lot after being spotted with a rangefinder," Hawley wrote in a letter.
