The disagreement never turned violent, according to Us, but Pressly and her assistant confronted Warren over a phone that Warren claimed was hers, but which Pressly said belonged to the assistant.
All three had been attending a birthday party in Los Angeles Friday night when Pressly's assistant noticed her phone was missing and used a locator application to track it to the Hollywood club Bootsy Bellows, Us reports. Pressly and her assistant went to the club, where they found Warren and other party guests including Zac Efron and Adam Lambert.
Pressly insisted the phone belonged to her assistant and was trying to retrieve it from Warren. Police were called after drugs were reportedly found in Warren's purse.
The investigation is still active, according to the report.