A suspicious package discovered at San Francisco International Airport on Friday morning led to the evacuation of a terminal and additional delays for travelers already impacted by weather delays, authorities said.

The San Francisco Police Department said that officers responded to Harvey Milk Terminal 1 at SFO at about 8:15 a.m. on a report of a suspicious package, and the area was evacuated. The department's bomb squad was dispatched to the site, police said.

SFO said the departures level lobby of Terminal 1 was closed, and an airport spokesperson said roadway traffic to the domestic terminals - Terminal 1, 2 and 3 - was rerouted to the International Terminal due to traffic congestion. 

The terminal re-opened at about 10:45 a.m., the airport said, although there was still heavy roadway congestion. Passengers were urged to give themselves additional time and consider being dropped off at the International Terminal and taking the AirTrain to their terminal.

Police spokesman Officer Robert Rueca could not say what the contents of the package were, but said a K-9 officer alerted that the package might have contained explosives.  

"It was a K-9 officer that alerted to the suspicious package," Rueca said. "The dog alerted the handler, and the handler determined that we needed to investigate."  

Police said the package was eventually deemed to be safe, but there was no immediate word of what the package was or who dropped it off. 

Rueca said investigators were reviewing surveillance camera footage to identify the person who left the package behind.

The incident added to ongoing weather delays at SFO, which has seen hundreds of arrivals and departures delayed after several days of strong winds and heavy rain.

On Thursday, the Federal Aviation Administration placed SFO under a ground delay program, which limits the number of aircraft that can land by delaying departures from other airports across the country.

The program is expected to last until midnight, but adverse weather conditions could continue to impact safety protocols. As of 2 p.m., SFO was restricted to 28 aircraft per hour, with the potential to increase.

Delays, according to the advisory, may reach an average high of 98 minutes. 

Aircraft tracking website FlightRadar24 showed average departure delays reaching an hour, while arrivals averaged 36 minutes. Aviation analytics company Cirium estimated more than 1,000 flights were scheduled at SFO alone, making it one of the busiest travel days of the holiday season. Flight tracking website FlightAware showed more than 400 flights were already delayed as of 1 p.m., while 26 were canceled.

United Airlines, which has its West Coast base at SFO, accounted for most of the delays, with more than 100. However, Delta, American, Alaska, JetBlue, and SkyWest saw the greatest number of cancellations, with about four each.

Travelers passing through SFO were urged to allow plenty of time to arrive at the airport and to check with their carriers regarding ongoing disruptions.