Three navies searched Southeast Asian waters for 10 missing U.S. sailors for a second day Tuesday as the Navy ordered a broad investigation into the performance and readiness of the Pacific-based 7th Fleet after the USS John S. McCain and an oil tanker collided east of Singapore. Aircraft from the amphibious assault ship USS America and ships and aircraft from the navies of Malaysia and Singapore were focusing their search east of the city-state where the two vessels collided around daybreak Monday at an approach to a busy shipping lane. The guided missile destroyer is now docked at Singapore's naval base and its crew is working on emptying compartments that flooded when the collision ruptured the McCain's hull at its waterline, the 7th Fleet said in a statement. Ship repair divers have also started assessments of the hull, the statement said. It was the second major collision in two months involving the 7th Fleet. Seven sailors died in June when the USS Fitzgerald and a container ship collided in waters off Japan. 'It is the second such incident in a very short period of time — inside of three months — and very similar as well,' Navy Adm. John Richardson, the chief of naval operations, told reporters at the Pentagon. 'It is the last of a series of incidents in the Pacific fleet in particular and that gives great cause for concern that there is something out there we are not getting at.' Richardson ordered a pause in operations for the next couple of days to allow fleet commanders to get together with leaders, sailors and command officials and identify any immediate steps that need to be taken to ensure safety. A broader U.S. Navy review will look at the 7th Fleet's performance, including personnel, navigation capabilities, maintenance, equipment, surface warfare training, munitions, certifications and how sailors move through their careers. Richardson said the review will be conducted with the help of the Navy's office of the inspector general, the safety center and private companies that make equipment used by sailors. There was no immediate explanation for the collision. Singapore, at the southern tip of the Malay Peninsula, is one of the world's busiest ports and a U.S. ally, with its naval base regularly visited by American warships. There was no indication the collision was intentional or that cyber intrusion or sabotage had occurred but the review will consider all possibilities, Richardson said. The McCain had been heading to Singapore on a routine port visit after conducting a sensitive freedom-of-navigation operation last week by sailing near one of China's man-made islands in the South China Sea. The collision between the guided missile destroyer and the Alnic MC oil tanker ripped a gaping hole in the destroyer's hull on its port side aft, flooding adjacent compartments including crew berths, machinery and communications rooms. It happened about 4.5 nautical miles (8.3 kilometers) from Malaysia's coast but the McCain was able to sail on to Singapore's naval base. Malaysia's Maritime Enforcement Agency said the area is at the start of a designated sea lane for ships sailing into the busy Singapore Strait. Janes, a defense industry publication, estimated the hull breach was 3 meters (10 feet) wide. The 7th Fleet said damage control efforts prevented further flooding. Five injured sailors were taken to a hospital in Singapore for medical treatment. One of the injured sailors, Operations Specialist 2nd Class Navin Ramdhun, posted a Facebook message telling family and friends he was OK and needed surgery for an arm injury. He told The Associated Press in a message that he couldn't say what happened. 'I was actually sleeping at that time. Not entirely sure.' The Singapore government said no crew were injured on the Liberian-flagged Alnic, which sustained damage to a compartment at the starboard, or right, side at the front of the ship some 7 meters (23 feet) above its waterline. The ship had a partial load of fuel oil, according to the Greek owner of the tanker, Stealth Maritime Corp. S.A., but there were no reports of a spill. Several safety violations were recorded for the oil tanker at its last port inspection in July, one fire safety deficiency and two safety-of-navigation problems. The official database for ports in Asia doesn't go into details and the problems apparently were not serious enough for the tanker to be detained. The Navy last week said the Fitzgerald's captain was being relieved of his command and other sailors were being punished after poor seamanship and flaws in keeping watch were found to have contributed to its collision. An investigation into how and why the Fitzgerald collided with the other ship was not finished, but enough details were known to take those actions, the Navy said. The McCain, based at the 7th Fleet's home port of Yokosuka, Japan, was commissioned in 1994 and has a crew of 23 officers, 24 chief petty officers and 291 enlisted sailors, according the Navy's website. The destroyer is named for two decorated World War II admirals who were the father and grandfather of U.S. Sen. John McCain. ___ Baldor reported from Muscat, Oman. AP writers Stephen Wright in Bangkok, Robert Burns in Amman, Jordan, Eileen Ng in Kuala Lumpur, Malaysia, Deb Riechmann in Washington and Ali Kotarumalos in Jakarta, Indonesia, contributed to this report.