Appellant seeks a reversal of his conviction of obstructing an officer (OCGA § 16-10-24), enumerating as error the denial of his motion for directed verdict of acquittal. We affirm.

The State’s evidence shows that on December 10, 1983, at approximately 4:00 a.m., Officer Guest, a DeKalb County police officer who was moonlighting as an apartment complex security officer, received a telephone complaint about loud music in the complex. Guest, wearing his official police uniform jacket, proceeded to the location of the apartment in question and knocked on the door. A Mr. Sickler answered the door, and when the officer requested that the music be turned down, Sickler responded by slamming the door. Guest made a second request and received the same response. He then withdrew some distance to wait and see if the music would be turned down. Sickler came outside and confronted the officer about his continued presence, threatening to call the police if he did not leave. Guest responded that he was waiting for the music to be turned down and that it was unnecessary to call the police since he was himself a police officer. Sickler returned to the apartment and, shortly thereafter, Guest, listening to his police radio, heard a call go out on a “suspicious person,” giving Guest’s clothing description and his location. He answered the call, identifying himself as the suspicious person, but requesting that officers be dispatched to the scene. Officer Whittington and Sergeant Harper arrived shortly thereafter, but the music had been turned off. Guest told the two officers what had transpired, and they all three went to the apartment and knocked on the door. Sickler again answered the door, but it was apparent that there were several other people in the apartment. A belligerent conversation between the police and the people in the apartment began, during which appellant identified himself as the resident of the apartment. Harper then instructed Whittington to take appellant outside the apartment and issue him a citation for violating a local noise ordinance. At Whittington’s direction, appellant stepped outside the apartment and started up the steps of the apartment building. After some instigation from the people in the apartment, appellant decided not to accom[*494] pany Whittington, turned around toward the apartment, and attempted to get past the officer. At that point, Whittington reached for appellant, who tried to get away. A fight ensued, and appellant was restrained and handcuffed by Whittington and Harper while Guest attempted to keep the other occupants of the apartment inside. Appellant was charged with violation of a local noise ordinance, public drunkenness, disorderly conduct, and obstruction of an officer, but was only tried on the obstruction charge.

Under OCGA § 16-10-24, “[a] person who knowingly and willfully obstructs or hinders any law enforcement officer in the lawful discharge of his official duties is guilty of a misdemeanor.” Appellant contends that his warrantless arrest for violating the local noise ordinance was unlawful, since the arresting officers, Whittington and Harper, did not hear the loud music, and that consequently appellant was entitled to resist arrest. He also argues that the State was required to prove the underlying offense that initially led the officers to act. We disagree.

To begin with, OCGA § 16-10-24 was obviously meant to cover obstruction of law enforcement officers in general by the use of violence, threat of violence, or other unlawful means. The statute was purposefully made broad with the intention to cover some actions which would not otherwise be independently unlawful. Hudson v. State, 135 Ga. App. 739 (218 SE2d 905) (1975). It is not necessary for the State to prove the underlying offense that causes the officers to act; it is only necessary to prove the elements of the obstruction statute, i.e., that the act constituting obstruction was knowing and wilful, and that the officer was lawfully discharging his official duties. Id. Cf. Kelley v. State, 171 Ga. App. 222 (319 SE2d 81) (1984). In the case before us, there is no question that appellant was acting knowingly and wilfully when he began struggling with the officers. Moreover, the officers were acting within the meaning of the statute since they were attempting to effectuate a lawful arrest.

A warrantless arrest is legal if any crime is committed in an officer’s presence or within his immediate knowledge. OCGA § 17-4-20. This Code section also applies to violations of municipal ordinances. State v. Koon, 133 Ga. App. 685 (211 SE2d 924) (1975). Whether or not an arrest violates the statutory provision depends on whether at the time of the arrest the officer had probable cause to make it, i.e., whether the officer had trustworthy information to warrant believing that appellant had committed an offense. Thompson v. State, 155 Ga. App. 101 (270 SE2d 313) (1980). When a police officer is the informant, his reliability is presumed as a matter of law. Quinn v. State, 132 Ga. App. 395 (208 SE2d 263) (1974). It is also well established that information obtained by one officer in an investigation may be used by another officer common to that investigation as a reliable basis for[*495] probable cause. Parker v. State, 161 Ga. App. 37 (3) (288 SE2d 852) (1982).

Here we have a situation in which one off-duty officer witnessed the alleged violation of a local ordinance, relayed that information to two on-duty officers who arrived at the scene shortly thereafter to investigate the matter, and all three officers then worked together to effectuate appellant’s arrest. Under those circumstances, all three officers were acting in the lawful discharge of their official duties, and appellant’s interference with them constituted a violation of OCGA § 16-10-24. See Duncan v. State, 163 Ga. App. 148 (1) (294 SE2d 365) (1982); Hudson v. State, supra.

We agree with the trial court’s assertion that it would have been “a foolish thing” to have required the off-duty officer to go get a warrant and come back while the other two officers waited at the scene of the incident, particularly since the off-duty officer, acting alone, could have arrested appellant without a warrant before the other two officers arrived. Common sense compels the trial court’s and our conclusion that it “made no difference who actually made the arrest.” The elements of OCGA § 16-10-24 having been proved at trial, the trial court did not err in denying appellant’s motion for directed verdict; in failing to charge the jury on the law of warrantless arrest; and in prohibiting appellant from arguing that his arrest was unlawful. Furthermore, appellant’s enumeration of error as to the trial court’s failure to inform him of the content of the court’s jury charge prior to argument is not supported by the record.

Judgment affirmed.