German club Kaiserslautern said Wednesday it had halted team training after three suspected positive tests for coronavirus.
The four-time German champions, now in the third division, said the three people concerned will be re-tested during the day.
They, and anyone who came into contact with them, have been placed in strict quarantine.
The two top divisions of the Bundesliga resumed the season behind closed doors last weekend after a two-month suspension, but play in the third division is suspended until 30 May.
Players, coaches and backroom staff are being regularly tested for the virus.
The German league has claimed its restart under stringent conditions that can serve as a blueprint for other leagues, but officials were forced to remind players of social distancing rules after several instances of hugging in goal celebrations in the weekend's matches.