Jamie Pressly's fight with Estella Warren in Hollywood on Friday (April 5, 2013) appears to have started over a stolen cell-phone. Pressly, of My Name is Earl fame, was enjoying herself at a birthday party in Los Angeles, until her assistant's phone went missing, leading to a nasty confrontation with Warren, 42. According to US Weekly, the police had to be called and the situation took hours to resolve.

An insider said Pressly, 35, simply wanted to get her assistant's phone back and that the confrontation could hardly be called a fight. Another source said Pressly and her assistant discovered that the phone had gone missing at the original party location, though used the "find my phone" application to track it down. Strangely, it tracked it to hotspot Bootsy Bellows, where Warren and several other guests including Zac Efron and Adam Lambert were continuing the celebrations. According to the source, Warren claimed the phone was hers once Pressly had arrived and confronted her. 

At one point, drugs were allegedly discovered in Warren's purse, which led to the police getting involved. "Jaime and her assistant were volunteering for a drug test. They said the drugs weren't theirs.It was this crazy mess," added the source.

An investigation into the whole furore is currently underway and West Hollywood police confirm they were called out to the Bootsy Bellows nightclub late on Friday evening.

Jamie PresslyEstella Warren
Jamie Pressly [L] At The Fox Winter Party and Estella Warren [R] At The Safe Haven Premiere