The Stellar Development Foundation said in a follow-up announcement that “[a]round 1:00 am PDT, the Stellar Development Foundation’s validator nodes temporarily stopped validating transactions on the Stellar network. The SDF’s public Horizon API instance is also temporarily down. However, the Stellar network is still online.”
SDF’s engineering team is working to determine the cause and to resolve the issue and bring SDF’s nodes back online as quick as possible. In an effort to ensure continuity, SDF is also actively working with all Tier 1 validators on the network.