The NFL faced widespread complications Saturday in its attempt to complete the season amid the coronavirus pandemic, with the Denver Broncos dealing with a severe quarterback shortage, the San Francisco 49ers potentially needing to relocate, and the Baltimore Ravens and Pittsburgh Steelers experiencing further issues ahead of a twice-rescheduled game that, if it can’t be played Tuesday, could force the addition of a week to the regular season.

The most pressing problems involved the Broncos, who were left without any quarterbacks eligible to play but remain scheduled to host the New Orleans Saints in a game Sunday, and the Ravens-Steelers game, which the league already has delayed from Thursday night to Sunday afternoon to Tuesday night. But the largest-scale issue was the predicament of the 49ers, who might need to move their operations for practices and home games because of new restrictions imposed by Santa Clara County.

The Broncos were left scrambling when quarterbacks Drew Lock, Brett Rypien and Blake Bortles were sent home from the team’s practice facility Saturday. They were placed in five-day quarantines after being identified by the NFL as high-risk close contacts to fellow quarterback Jeff Driskel, who reportedly tested positive for the coronavirus Thursday. The quarantines were confirmed by a person familiar with the situation. All four of those quarterbacks are ineligible to play Sunday.

The Broncos-Saints game remained on as scheduled, according to a person familiar with the NFL’s planning. League officials have said they don’t postpone games over competitive issues while also warning teams that players must wear masks and follow protocols to reduce their chances of being identified as high-risk close contacts.

The Broncos quarterbacks were not forthcoming when dealing with contact tracers while the NFL and NFL Players Association were investigating the case, according to a person familiar with the situation. They were classified as high-risk close contacts after new information surfaced Saturday, according to that person, who added that Lock, Rypien, Bortles and Driskel were in a meeting room together for a “significant length of time” without masks.

In an Oct. 13 memo to teams, NFL Commissioner Roger Goodell wrote, “In light of the substantial additional roster flexibility in place for this season, absent medical considerations, games will not be postponed or rescheduled simply to avoid roster issues caused by injury or illness affecting multiple players, even within a position group.”

The Broncos don’t have another quarterback on their roster or practice squad. But their practice squad includes wide receiver Kendall Hinton, a quarterback during part of his collegiate career at Wake Forest. Running back Royce Freeman reportedly is the emergency quarterback on the roster, and the Broncos could use a wildcat formation at times Sunday with a direct snap to a running back.

The NFL and the 49ers have a contingency plan in place for where the team will practice and play games if it must move, according to a person familiar with the situation. Details were not immediately available, but games probably will be played at another NFL stadium. The league and team worked on contingency plans for months because of concerns about potential restrictions by the county. The 49ers first will attempt to work with the county before implementing the contingency plan, according to the person with knowledge of the deliberations.

“We are aware of the Santa Clara County Public Health Department’s emergency directive,” the 49ers said in a statement. “We are working with the NFL and our partners on operational plans and will share details as they are confirmed.”

NFL spokesman Brian McCarthy said, “We’re in contact with the club.”

As part of the directives announced Saturday by Santa Clara County, contact sports at the professional, collegiate and youth levels are temporarily prohibited.

“All recreational activities that involve physical contact or close proximity to persons outside one’s household, including all contact sports, will be temporarily prohibited,” the county said. “People can continue to engage in outdoor athletics and recreation where social distancing can be maintained at all times.”

Sara Cody, the Santa Clara County health officer, said in a statement: “I am gravely concerned by the continuing surge in COVID-19 cases and hospitalizations. The number of patients hospitalized with COVID-19 in our county has doubled in just the past couple of weeks, and we are at risk of exceeding our hospital capacity very soon if current trends continue.”

The 49ers play Sunday in Inglewood, Calif., against the Los Angeles Rams. Their next scheduled home game is Dec. 7, a Monday night, against the Buffalo Bills. The 49ers also have home games scheduled for Dec. 13 against the Washington Football Team and Jan. 3 against the Seattle Seahawks.

The NFL told teams Saturday that all team facilities are closed Monday and Tuesday because of rising coronavirus caseloads nationally and Thanksgiving gatherings. All teams’ operations on those days must be virtual. Teams playing games Monday and Tuesday are exempt. That means the 49ers could need a new practice site by Wednesday.

The Ravens had one additional positive test result by a player returned Saturday evening, according to a person familiar with the results. The game remained scheduled for Tuesday, according to a person with knowledge of the NFL’s planning, and some of the players on the Ravens’ covid-19 reserve list might be eligible to play by then. Approximately 14 Ravens players, including quarterback Lamar Jackson, and a significant number of staff members have tested positive for the coronavirus in recent days.

The Ravens placed six more players on their covid-19 reserve list Saturday: linebacker Jaylon Ferguson, defensive lineman Broderick Washington, cornerbacks Khalil Dorsey and Tavon Young, and offensive linemen D.J. Fluker and Will Holden. That list is for players who test positive for the coronavirus and those determined through contact tracing to have been exposed to it. The Steelers placed running back James Conner on their covid-19 reserve list Saturday after he reportedly tested positive.

If the game can’t be played Tuesday, the NFL might have to add a Week 18 to its regular season. League officials have said they would do that if all games cannot be played in the current 17-week format. The Steelers and Ravens already have had their bye weeks.