Updated

An e-mail warning of a weekend bloodbath has alarmed the Mexican border city of Ciudad Juarez, which has already seen a wave of killings.

Nobody seems to know who wrote the e-mail, which says gunmen will fire at malls, restaurants and other public places in "killings all over the city." But many have forwarded it to friends.

Ciudad Juarez Police Chief Roberto Orduna says the threats must be taken seriously. He issued a news release Thursday assuring residents that police would be more vigilant.

Officials say more than 200 people have been killed so far this year in Juarez, a city of 1.3 million people across from El Paso Texas. Most of the deaths are blamed on battling drug cartels.