Online staffing firm TaskRabbit’s website was back online Thursday; it had been down in response to a cybersecurity incident earlier this week.

TaskRabbit CEO Stacy Brown-Philpot discussed the incident in a post on the company’s website.

“While our investigation is ongoing, preliminary evidence shows that an unauthorized user gained access to our systems,” Brown-Philpot wrote. “As a result, certain personally identifiable information may have been compromised.”

She continued: “We have an outside forensics team working diligently to determine what information may have been compromised, and will notify every affected individual, but as an immediate precaution, Taskers and Clients should monitor their accounts for any suspicious activity. Also, anyone who uses their TaskRabbit password on other websites and apps should change them.”