BERLIN (AP) — Police in the German capital are appealing for witnesses to help find a cyclist who sprayed at least half a dozen women with liquid, injuring several, in the past three months.

Berlin police say the attacks began Dec. 7 and in at least four cases battery acid was sprayed at the women. All happened in the northeast of the capital. One woman suffered serious facial injuries in an attack.

In a statement, police said a 41-year-old woman who was attacked shortly after midnight described the man as about 35-45 years old, light-skinned and wearing a baseball cap.

Spokeswoman Valeska Jakubowski said Tuesday that police weren't providing specific safety advice to women at this time. "It's difficult to predict these attacks, but we're working hard to find the culprit," she said.