From https://local.nixle.com/alert/5158689/?sub_id=168810

9-1-1 (Voice and TDD/TTY) For Life-Threatening Emergencies Only 
Crime prevention cannot be achieved by the police alone. Together professional law enforcement officers must work hand-in-hand with the public to fight crime and neighborhood disorder throughout our communities. As such, we depend heavily on your assistance in reporting crimes to the police. The following hotline numbers are provided for your use and convenience.

TEXT-A-TIP 
To provide anonymous tips, text CRIMES (274637) on your cell phone and begin the message with the letters LAPD.

You may submit an anonymous tip anytime, anywhere, 24 hours a day, 7 days a week, by phone 800-222-TIPS (800-222-8477)

Some other numbers that may be helpful are: 

Abandoned Vehicles 
800-ABANDON (222-6366)

Battered Women Hotline 
310-392-8381

Child Abuse 
800-540-4000

Graffiti Problems 
(City of L.A. 3-1-1)

Mothers Against Drunk Drivers MADD 
310-215-2905

Narcotics Hotline 
800-662-BUST (2878)

Narcotic Drug Abuse 
800-252-6465

Rape Hotline 
626-793-3385

Runaway Hotline 
800-551-1300

Suicide Hotline 
877-727-4747

Terrorist Threats 
1-877-A-THREAT (284-7328)