Why and how police Make PANCHNAMA

It is essential that a panchanama, in respect of an arrest, search, seizure etc. should always be made at the site of the occurrence of the accident or offence and the signatures of the panchas/witnesses should be obtained thereon.
An accused/a person whose premise has been searched, must get a copy of the Panchnama.
It is necessary that two panchas remain present while a Panchanama is being drawn and their signatures should be obtained on it.
After paying the fees, in form ‘AA’, a copy of the Panchanama drawn at the site of an accident can be obtained.
Courtesy: https://mumbaipolice.maharashtra.gov.in/panchnama.asp